Initial commit

Just enough to prove that the app will read from the configuration file
and can talk to the Twitter API with the provided credentials.
Serve bare homepage or 404
Add bare HTML homepage template
Add code to sign in via Twitter
Store session data in Redis, not in memory

This means it persists across restarts of the app.
Add ability to tweet on behalf of central account
Add pre-configured tweet actions
Move $twitter into the response section

This stops the access tokens being overwritten when a new user
logs in, and suddenly we're tweeting from the wrong account.
Catch Twitter API errors when posting updates
Add context to tweets

This allows `%context` to be added to pre-baked tweets, which will be
expanded to the current value before tweeting.

Good for hashtags and such.
Don't allow actions unless user is authenticated