Merge pull request #652 from urfave/travis-tweaks

Update travis config

.travis.yml

@@ -1,28 +1,17 @@
 language: go
-
 sudo: false
+dist: trusty
+osx_image: xcode8.3
+go: 1.8.x
+
+os:
+- linux
+- osx
 
 cache:
   directories:
   - node_modules
 
-go:
-- 1.6.x
-- 1.7.x
-- 1.8.x
-- master
-
-matrix:
-  allow_failures:
-  - go: master
-  include:
-  - go: 1.6.x
-    os: osx
-  - go: 1.7.x
-    os: osx
-  - go: 1.8.x
-    os: osx
-
 before_script:
 - go get github.com/urfave/gfmrun/... || true
 - go get golang.org/x/tools/cmd/goimports