Find out how to package runtimes.json into wskdeploy binary

[pritidesai]

As a quick fix in PR #1017, I have moved runtime json into runtimes.go but we want to bring back runtimes.json back to maintain portability of wskdeploy where for adding any new runtime, we can just update the json file. I found a way to bundle json into wskdeploy binary using packr but need to look into it more and see how we can make it part of binary.

[rabbah]

This should not exist in wskdeploy - the tool should IMO read it from the API host.