Remove redundant bloat from API modules.

This generalizes the implementation of the following methods:

 * getVersion()
 * getHelpUrls()
 * needsToken()
 * mustBePosted()

These methods have been pulled up into the Api base class.

Change-Id: Ic62cfac9819b64ecd987c44d75a54a68db77e33f
Merge "Remove redundant bloat from API modules."