welcome pyrrit, deprecate pstest

pyrrit can do what pstest can, and moar.

pyrrit can handle multiple pulls
for eg. pyrrit pull 17223 17224 17235

pyrrit's pull function can be executed
from top. path wont matter.

pyrrit can list all open changes on gerrit
or list open changes by project

Change-Id: I27f68d70be8e0b84d6555513db91589fba38c817
Signed-off-by: Arnav Gupta <championswimmer@aokp.co>