Update Travis file

Using container-based infrastructure by setting sudo to false
Test on Go 1.5

Author: marksamman

.travis.yml

@@ -1,3 +1,4 @@
+sudo: false
 language: go
 
 go:
@@ -6,5 +7,6 @@ go:
   - 1.2
   - 1.3
   - 1.4
+  - 1.5
 
 script: go test