chore(build): test on all officially supported node versions

Author: keithamus

.travis.yml

@@ -6,9 +6,12 @@ cache:
   directories:
   - node_modules
 node_js:
-- 0.1
-- 4.3
-- stable
+ - 0.10 # to be removed 2016-10-31
+ - 0.12 # to be removed 2016-12-31
+ - 4 # to be removed 2018-04-01
+ - 6 # to be removed 2019-04-01
+ - lts/* # safety net; don't remove
+ - node # safety net; don't remove
 before_install:
 - npm i -g npm
 script: