fix coverage path.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

.travis.yml

@@ -20,5 +20,5 @@ install:
 
 script:
   - cd gopush && go test -v -covermode=count -coverprofile=coverage.out
-  - $(go env GOPATH | awk 'BEGIN{FS=":"} {print $1}')/bin/goveralls -coverprofile=gopush/coverage.out
+  - $(go env GOPATH | awk 'BEGIN{FS=":"} {print $1}')/bin/goveralls -coverprofile=coverage.out
     -service=travis-ci -repotoken=$COVERALLS_TOKEN