added feedback edits and use cases to docs
Merge pull request #12 from jtmoulia/doc-feedback

added feedback edits and use cases to docs
added client-based worker interface

This change involved refactoring the command flow in
`switchboard_jmap`.
Merge branch 'worker-interface' of https://github.com/jtmoulia/switchboard into worker-interface

Conflicts:
	site/guide/client.md
Merge branch 'worker-interface'
added .travis.yml for R15+R16 using erlang.mk