Twit 02 Retrieve user twitter home stream

Creates a generic parser and requester. Performing a request against the REST api now requires the correct pair. 

Example:
To request the twitter android dev stream, the request requires the TwitterObjectRequester (Twitter responds with a JsonObject) and the TweetsHashTagParser to parse the Json object.


Moved the activity out of the constructor. I still need to pass it to the OAuthRequester to create a `startActivityForResult`