Created new library to handle Twitter retrieval

@thisisgreg I removed the old ezTweet auth and fetch PHP library with the one file that's now in `source/plugins/twitter`. This also includes removing the `jquery.tweet.js plugin`. Twitter API auth seemed to change and I guess the old plugin/library didn't support it or something?

You will need to do one thing more before this works.:
* Create an app here under TMI's Twitter account: https://apps.twitter.com/
* Creating the app will give you an API key and an API secret. You can then do one of two things:
  * On the server the site lives on, set environment variables for `TMITWEETS_CONSUMER_KEY` and `TMITWEETS_CONSUMER_SECRET' equal to your API key and secret.
  * Or if you don't care about people potentially coming across this repository and seeing your key and secret, in `source/plugins/twitter/index.php` on lines 94 and 95, change the `FALSE`s to strings with your key and secret.
    * You can at least try this on your own computer before pushing to the server if you wanna try it out locally.

Fixes #1