drop Travis test on Julia v0.5

Author: Hua-Zhou

.travis.yml

@@ -4,7 +4,6 @@ os:
   - linux
   - osx
 julia:
-  - 0.5
   - 0.6
   - nightly
 matrix:
@@ -25,4 +24,4 @@ notifications:
     on_success: change
     on_failure: always
   recipients:
-    - esobel@ucla.edu
+    - huazhou@ucla.edu