Make a few minor updates to node shell help strings

Make a few minor updates to node shell help strings

Change-Id: I588b62108ea610b5c21f9ce9bc2a97841ac574f3
Add CONTRIBUTING.rst

There is no CONTRIBUTING.rst file, the patch will add it.

Change-Id: I129af2c2301c47df5619f4fe279127b68f974098
Use suitable assert

Replace assertTrue(a is None) with assertIsNone(a)

Change-Id: I1877e7615b45336e644c6e005349432bc71a4b79
Merge "Add CONTRIBUTING.rst"
Merge "Use suitable assert"