Modernize Paste

Summary:

• Add a PhabricatorApplication.
• Make most of the views work well on tablets / phones. The actual "Create" form doesn't, but everything else is good -- need to make device-friendly form layouts before I can do the form.

Test Plan: Will attach screenshots.

Reviewers: btrahan, chad, vrana

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1569

Differential Revision: https://secure.phabricator.com/D3293