Add Parsoid to the list of deployed extensions

The Parsoid PHP extension optionally performs internal HTTP requests to a
Parsoid service on edit and refreshLinks jobs. It is implemented using the job
queue, and was reviewed by Aaron.

See
http://www.mediawiki.org/wiki/Parsoid/Minimal_performance_strategy_for_July_release
for background.

Change-Id: I5f674593b8514b2b548d22696125f59b00eb8a22