R1:6bebb3c69a07

Add "and" support to "ref"

Summary: Fixes T8038. Allow `PhabricatorCustomFieldMonogramParser` to handle "and". This means that `Ref Tx, Ty and Tz` will correctly return `array('monograms' => array('Tx', 'Ty', 'Tz')`.

Test Plan: Added unit tests.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley

Maniphest Tasks: T2, T3, T1, T8038

Differential Revision: https://secure.phabricator.com/D12682