Paste - kill tabs

Summary:
merge paste create and paste list into a single controller. Add a "filter list"
to the left hand side and have new "create w/ recent", "my" and "all" views. UI
wrinkle -- "create w/ recent" does not paginate the recent pastes and instead
upsells the user to the new "all" view.

Also includes a business logic clean up or two for simplicity of code.

Test Plan:

• created a paste from the UI
• tried to create a paste with title and no body
• tried to create a paste with no title and no body
• viewed the paste list on "create" view
• viewed the paste list on "author" view
• viewed the paste list on "all" view
• viewed page 2 of the paste list for "author" and "all" views
• "forked" a given paste through completion

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley, btrahan

Maniphest Tasks: T631

Differential Revision: 1198