CBD-761: convert t folder to python package

also change permissions for pump_test.py (-x) so that it can be
auto-discovered by nosetests.

Change-Id: I944333e3cb188a022a2e23287bb382c5783fb749
Reviewed-on: http://review.couchbase.org/23913
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>