v0.0.2

Fixes:

* Repository descriptions were not set to the corresponding GitHub
  description when mirroring repositories on Linux.
* Empty repositories with no branches or commits now have their mtime
  set correctly.

Changes:

* Set repository mtime to GitHub `pushed_at` time instead of
  `updated_at` time.
* Change HEAD to GitHub's default branch and set CGit's default branch
  to match.