Add multi-service support

[kraman]

• Use service package name as identifier
• Create service if it doesnt exist
• Update tests to support service find and create endpoints

Connect to strongloop-internal/scrum-nodeops#417

[sam-github]

There are no docs in the usage message for how to deploy multiple apps!

[sam-github]

and -c/config should be removed... multiapp pm no longer has any config support.

[kraman]

/cc @chandadharap . I ran the help text by @crandmck and he was concerned about the confusion between naming terms:

• application vs APIs vs service
• service (as used in mesh) vs operating-system service

Perhaps we should set up a short discussion and hash this out before we complete multi-app PM

[sam-github]

LGTM