Updates for newer version of python-twitter (new twitter API)

These are changes to support what will eventually be version 3.2 of
python-twitter; for the time being we are running of a git clone of
the devel branch, which supports the newer twitter API (so e.g. tweets
quoting other tweets work properly); it doesn't look like an upstream
release of 3.2 is going to happen any time soon.

Author: Adam Bernard
Signed-off-by: Matthew Vernon