Updates to README.md and CODING.md.

Describe how to report bugs, install grunt, and update jsduck instructions.
Fix path to license file in package.json.

Change-Id: I276ff0ea4324f027dafc044a86fa564b2439089a
Updates to support jsduck 5.x.

Change-Id: I16123e91370cb6a7785060c749530953f4c3ddf4