Add v1.1 upgrade script

[jasonmp85]

We added a new user-facing function in #56 but did so directly in the main pg_shard SQL file. We need to bump our version number and add an upgrade script. I'm thinking during develop the script (and version) should be named develop or something and we can fill it in with a real version number during release. This will always give us a placeholder to add new functions during development and then we can "freeze" that version during release by renaming the file to the actual version being released.