travis: run with ginkgo -p instead of go test

may help reduce test-pollution due to namespace-affinity

see http://onsi.github.io/ginkgo/#parallel-specs

.travis.yml

@@ -8,7 +8,7 @@ go:
 
 env:
   global:
-  - PATH=$GOROOT/bin:$PATH
+  - PATH=$GOROOT/bin:$GOPATH/bin:$PATH
   matrix:
   - TARGET=amd64
   - TARGET=arm
@@ -19,6 +19,9 @@ env:
 matrix:
   fast_finish: true
 
+install:
+  - go get github.com/onsi/ginkgo/ginkgo
+
 script:
  - |
    if [ "${TARGET}" == "amd64" ]; then