Update .travis.yml, set GO15VENDOREXPERIMENT=1"

Author: spinlock

.travis.yml

@@ -1,16 +1,12 @@
 language: go
 
-env:
-    - GO15VENDOREXPERIMENT=0
+os:
+    - linux
+    - osx
 
 go:
-    - 1.5.3
-    - 1.4.3
-    - 1.3.3
-    - 1.6
-
-install:
-    - go get -u github.com/tools/godep
+    - 1.6.2
+    - 1.5.4
 
 script:
     - make gotest