DownloadRunnableFallback: Fix error with log tag being too long

Abbreviate Download -> DL

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

Author: theimpulson

app/src/main/java/us/shandian/giga/get/DownloadRunnableFallback.java

@@ -21,7 +21,7 @@
  * Single-threaded fallback mode
  */
 public class DownloadRunnableFallback extends Thread {
-    private static final String TAG = "DownloadRunnableFallback";
+    private static final String TAG = "DLRunnableFallback";
 
     private final DownloadMission mMission;