Issue #90: Move to direct-call framework design ...

Rather than signalling events everywhere and letting extension plugins
handle them if they choose to, the framework should be reworked to
directly call functions on the appropriate integration plugin. This will
both reduce overhead from events and simplify plugin work by removing if
statements at the beginning of every event handler.

This will require follow-on changes to all source integration plugins to
work with the new parent class API.

Version bump in Source plugin to signify API changes.

Allow for correct processing of re-imported repos

Fix #28: Updated copyrights from '20081 to '2008-2009'

Fix #14: Implemented repeating import events until no more changesets imported.

Fix #13: Convert project license to AGPL3.

Issue #3: Pull resolution status from configuration threshold; various tiny tweaks.

Issue #2: Set up commit and import pages to handle parsing buglinks and saving changesets.

Added form security tokens to repo/management pages.

Textual and error reporting enhancements.

Missed some necessary changes from the new API.

Added stub functionality for differentiating between full and partial imports.