use python twitter tools to connect to twitter api

Changes `TwitterTaskHandler` to use the [Python Twitter Tools](https://github.com/sixohsix/twitter) module to connect to twitter api with application specific oauth credentials. 

I have created a config module that uses key-value pairs to store API credentials (could also be used for other APIs). I have included a skeleton file that does not contain the actual keys. It is formatted to work if you just drop in keys and tokens. I will be happy to share our app's keys via email, or you can just enter your own. 

This commit includes a complete copy of the PTT source, which I had to modify slightly to exclude a reference to a C module (_ssl) that Google App Engine does not support. So unless we find a work around, we'll have to keep it in the repo. 

I tested locally, and everything worked just fine. Please let me know if there is anything I need to change, especially where my code is not 'pythonic'. I tried to stick to the conventions already shown, but I may have missed something. Thanks!