Remove links to maniphest, phriction in tactical command, jump nav

Summary:
We don't use maniphest or phriction in our install, so the links/references to
them in tactical command and jump nav can be confusing for users. This hides
these elements if they aren't enabled.

Test Plan: loaded the front page of phabricator in my sandbox, saw they went
away

Reviewers: epriestley, btrahan, jungejason

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1636