update .travis.yml

Author: Dean Karn

.travis.yml

@@ -31,5 +31,8 @@ script:
  - find . -type f | xargs misspell -source=text
  - go test -v ./...
  - go test -race
- - overalls -project="github.com/go-playground/pure" -covermode=count -ignore=.git,examples -debug
- - goveralls -coverprofile=overalls.coverprofile -service travis-ci -repotoken $COVERALLS_TOKEN
+
+after_success: |
+  [ $TRAVIS_GO_VERSION = 1.8.1 ] &&
+  overalls -project="github.com/go-playground/pure" -covermode=count -ignore=.git,examples -debug &&
+  goveralls -coverprofile=overalls.coverprofile -service travis-ci -repotoken $COVERALLS_TOKEN