Make Maniphest Transaction preview tokenizer aware
Summary:
...pretty sure the JS is too hack-tastic but it works...! :D
also fixed a small error from assert_instances_of change where a null value is all errors and what have you
Test Plan: played around with tasks in firefox and safari. made cc, owner, and project changes, as well as priority, etc.
Reviewers: epriestley
Reviewed By: epriestley
CC: aran
Maniphest Tasks: T1074
Differential Revision: https://secure.phabricator.com/D2234