R1:f55aac49f4d7

Rename "pastebin" database to "paste"

Summary:
See D20650. Long ago, this got added as "pastebin", but that's the name of another product/company, not a generic term for paste storage.

Rename the database to `phabricator_paste`.

(An alternate version of this patch would rename `phabricator_search` to `phabricator_bing`, `phabricator_countdown` to `phabricator_spacex`, `phabricator_pholio` to `phabricator_adobe_photoshop`, etc.)

Test Plan:
- Grepped for `pastebin`, now only found references in old…