remove unused dependency in travis config

.travis.yml

@@ -3,11 +3,6 @@ language: go
 go:
   - 1.6.3
   
-before_install:
-  - go get golang.org/x/tools/cmd/cover
-  - go get github.com/onsi/gomega
-  - go get github.com/onsi/ginkgo
-
 script:
   - go test -tags json github.com/v2ray/v2ray-core/...