Test malformed dates, raise a proper error.
Rework the test suite a bit.
Add vim swap files to .gitignore
Move most of the ironblogger script to a module.

This will make testing it easier.
Test syncing multiple blogs, one of which has a bad post.

We should still sync the feeds we *can* parse.

The test exposed an issue with the way _app_context was being used in
the cli -- we were never cleaning up after ourselves. We now just use a
with statement.
Clean up tempfiles in sync_posts test.