Add the integration tests in Go

Travis CI is now running the scala integration tests in openwhisk cli for this repo. We need to write the integration tests in Go by implementing the REST API of openwhisk for all the listed openwhisk api functions.

Start by locating the existing Scala integration tests run by Travis CI and the list of OpenWhisk API functions referenced in the repository. Compare their coverage with the Go client’s REST API entry points, then add Go integration tests for all listed functions and verify that they pass in Travis CI.

Written by the indexing model from the issue text.