Fix announcements feature by changing template format from $FOO to {FOO} so it doesn't conflict with bash

Previously it wasn't broken, just confusing (to me and likely to others) since:

```
export ANNOUNCEMENT="Hello I'm $USERNAME"
```

Would have $USERNAME replaced by an empty string (since the environment variable isn't set). The fix is
relatively easy (just escape the $ like `\$USERNAME`) but non-obvious. So it seemed better to just use
{FOO} as the format since it doesn't conflict with that.

Author: ddworken

docs/env.md

@@ -93,17 +93,17 @@ the bot is started. This is useful if you would like the bot to announce the fac
 a given team. The `ANNOUNCEMENT` environment variable supports a number of templating variables that will be instantiated
 based off of the current config. These are:
 
-* `$USERNAME` will be replaced with the username of the bot
-* `$CURRENT_TEAM` will be replaced with the team that the message is being sent in
-* `$TEAMS` will be replaced with the comma separated list of teams that the bot is running in
+* `{USERNAME}` will be replaced with the username of the bot
+* `{CURRENT_TEAM}` will be replaced with the team that the message is being sent in
+* `{TEAMS}` will be replaced with the comma separated list of teams that the bot is running in
 
 Examples:
 
 ```bash
 export ANNOUNCEMENT="SSH CA bot starting up..."
-export ANNOUNCEMENT="Hello! I'm $USERNAME and I'm an SSH bot! See github.com/keybase/bot-sshca for information on using Keybase for SSH."
-export ANNOUNCEMENT="Hello! I'm $USERNAME and I'm an SSH bot! I'm currently listening in $TEAMS."
-export ANNOUNCEMENT="Hello! I'm $USERNAME and I'm an SSH bot! Being in $CURRENT_TEAM will grant you SSH access to certain servers. Reach out to @dworken for more information."
+export ANNOUNCEMENT="Hello! I'm {USERNAME} and I'm an SSH bot! See github.com/keybase/bot-sshca for information on using Keybase for SSH."
+export ANNOUNCEMENT="Hello! I'm {USERNAME} and I'm an SSH bot! I'm currently listening in {TEAMS}."
+export ANNOUNCEMENT="Hello! I'm {USERNAME} and I'm an SSH bot! Being in {CURRENT_TEAM} will grant you SSH access to certain servers. Reach out to @dworken for more information."
 ```
 
 ## Developer Options

src/keybaseca/bot/bot.go

@@ -152,14 +152,14 @@ func isConfiguredTeam(conf config.Config, teamName string, channelName string) b
 
 func buildAnnouncement(template, username, currentTeam string, teams []string) string {
 	replacements := map[string]string{
-		"$USERNAME":     username,
-		"$CURRENT_TEAM": currentTeam,
-		"$TEAMS":        strings.Join(teams, ", "),
+		"{USERNAME}":     username,
+		"{CURRENT_TEAM}": currentTeam,
+		"{TEAMS}":        strings.Join(teams, ", "),
 	}
 
 	templatedMessage := template
-	for template, val := range replacements {
-		templatedMessage = strings.Replace(templatedMessage, template, val, -1)
+	for templateStr, templateVal := range replacements {
+		templatedMessage = strings.Replace(templatedMessage, templateStr, templateVal, -1)
 	}
 
 	return templatedMessage

src/keybaseca/bot/bot_test.go

@@ -12,11 +12,11 @@ func TestBuildAnnouncement(t *testing.T) {
 	require.Equal(t, "no templates",
 		buildAnnouncement("no templates", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
 	require.Equal(t, "repeated my_username my_username my_username",
-		buildAnnouncement("repeated $USERNAME $USERNAME $USERNAME", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
+		buildAnnouncement("repeated {USERNAME} {USERNAME} {USERNAME}", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
 	require.Equal(t, "all my_username my_cur_team my_team1, my_team2",
-		buildAnnouncement("all $USERNAME $CURRENT_TEAM $TEAMS", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
-	require.Equal(t, "bogus $FOO",
-		buildAnnouncement("bogus $FOO", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
-	require.Equal(t, "double-is-not-escape $my_username",
-		buildAnnouncement("double-is-not-escape $$USERNAME", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
+		buildAnnouncement("all {USERNAME} {CURRENT_TEAM} {TEAMS}", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
+	require.Equal(t, "bogus {FOO}",
+		buildAnnouncement("bogus {FOO}", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
+	require.Equal(t, "double-is-not-escape {my_username}",
+		buildAnnouncement("double-is-not-escape {{USERNAME}}", "my_username", "my_cur_team", []string{"my_team1", "my_team2"}))
 }

tests/envFiles/test_env_1

@@ -7,4 +7,4 @@ export KEYBASE_PAPERKEY="$BOT_PAPERKEY"
 export KEYBASE_USERNAME="$BOT_USERNAME"
 export CHAT_CHANNEL="$SUBTEAM.ssh#ssh-provision"
 export CA_KEY_LOCATION="/shared/keybase-ca-key"
-export ANNOUNCEMENTS="Hello my name is $USERNAME. This is $CURRENT_TEAM and the configured teams are $TEAMS"
+export ANNOUNCEMENT='Hello my name is {USERNAME}. This is {CURRENT_TEAM} and the configured teams are {TEAMS}'