Twitter news integration

This addon fixes the broken ocPortal Twitter support. ocPortal originally supported Twitter, but very recently Twitter turned off the support we used, and now only supports a much more complex method, oAuth. This adds full oAuth Twitter integration back into ocPortal.

The code is based on 'Twitter class' by 'Tijs Verkoyen'.

PHP5 is required, and the PHP CuRL extension is required. Integration is more tricky, you need to set up an application on Twitter, and post a test message to authorise before you can post messages for real. This is explained in the configuration options (which are implemented on top of the inbuilt ocPortal ones).