make database table names shorter and more consistent

Also:
* Try to fix a pagodabox issue i noticed in which auto_increment adds an increment of 4 rather than 1 to each index.  That's apparently useful for some sorts of database replication scenarios, but i'm pretty sure it's not what we want.
* clarify grunt README

Important note: when you apply this update, if you have an existing database, you must run the SQL file:
deploy/database/updates/001_drop_old_table_names.sql
This file removes tables which are no longer used.  If you are creating a fresh database from scratch, you do *not* need to run this file, which is why i didn't add it to initialize_all.sql