Summary:
Ref T2625. Currently, custom saved queries can be edited but not deleted. Allow them to be deleted. Also:
- Clean up an unused property in `PhabricatorPasteViewController`.
- Fix an issue with left nav highlighting of builtin queries.
- Improve submit behavior for edits.
- Add a cancel button on edits.
Test Plan: Saved, edited and deleted queries.
Reviewers: btrahan, blc
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T2625
Differential Revision: https://secure.phabricator.com/D6059
