phlcon_differential__t: fix bug detected by pylint

'update_revision_empty' doesn't return anything, don't assign return
value.

Add 'pylint' to static_tests but commented out, doesn't seem to add
significant value at this point.

Test Plan: $ ./precommit.sh
Arcyd: support branch/review url format strings

Allow linking to branch / review pages by accepting format string
parameters.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/status_html_testbed.sh
Arcyd: refactor: abdt_reporeporter: hide func

Hide 'branch_status_to_string', it's only used internally.

Test Plan: $ ./precommit.sh
Arcyd: report 'no users on branch'

User 'reporter' in addition to 'mailer' when trying to create awareness
of a branch which has no discoverable Phabricator users on it.

Test Plan:
$ ./precommit.sh
$ ./testbed/arcyd/status_html_testbed.sh
Arcyd: refactor: remove redundant commenter create

Test Plan: $ ./precommit.sh
Arcyd: mention repository and branch url on create

When creating a new review, mention the repositiory that it was created
from and the URL to browse the contents of the branch (if configured).

This makes it easier to determine the origin of a change and to get the
full context when a review is too big to be fully displayed in
Phabricator.

Store the new information in the abdt_branch, test that both branch and
branchmock store and retrieve correctly.

Add link formatting support to abdt_remarkup.

Test Plan: $ ./precommit.sh