add coveralls test coverage stats

.travis.yml

@@ -23,7 +23,11 @@ before_script:
 script:
   - diff -u <(echo -n) <(gofmt -d ./pkg ./cmd ./tools)
   - make openapi
-  - make all
+  - make all && $HOME/gopath/bin/goveralls -coverprofile=cover.out -service=travis-ci -repotoken $COVERALLS_TOKEN
+
+install:
+  - go get golang.org/x/tools/cmd/cover
+  - go get github.com/mattn/goveralls
 
 deploy:
   skip_cleanup: true