Summary: Adds support for the "encoding" field to the new transactional interface.
Test Plan:
{F44189}
{F44190}
Some of the encodings in the second screen are from testing, and can no longer be set.
Reviewers: btrahan, chad
Reviewed By: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D6035
