Add ssh package to the build

The ssh package is not part of the standard library in go 1.5.

Author: ccojocar

.travis.yml

@@ -7,6 +7,7 @@ go:
 install:
   - go get -v github.com/onsi/ginkgo/ginkgo
   - go get -v github.com/onsi/gomega
+  - go get -v golang.org/x/crypto/ssh
   - go get -v -t ./...
   - export PATH=$PATH:$HOME/gopath/bin