With the new Heartbleed vulnerability in the wild, GitHub recommends

resetting all authentication tokens, just to be sure. This change

introduces a management command that makes that somewhat easy.
This command will loop through all GitHub accounts that are linked to

Review Board, resetting their tokens and replacing them new, valid

tokens.
If using a registered GitHub OAuth app for Review Board, then the resets

won't require any credentials. However, for personal tokens (which is

the standard case), it will require a password, and possibly a

two-factor auth token.

Reset a valid working personal OAuth token.
Reset an OAuth token I had locally that had no corresponding entry on GitHub. Saw it create a valid entry.
Reset an OAuth token backed by a registered OAuth app.
In each case, I verified the token payload contents and verified that I could fetch files from GitHub in the diff viewer.
Tested the --yes and --local-sites options.
Unit tests pass.