Change All Search Boxes into Jump Navs

Summary:

• all search boxes are now jump navs (old functionality retained if none of the jump nav patterns match)
• added global keyboard shortcut '/' to focus the search box in the upper right

Test Plan:

• pressed '/' and noticed the search box gains keyboard focus
• triggered jump nav functionality from search box and saw it worked
• did a search which did not match a jump nav pattern and saw it worked (and searched in the selected context)

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1794