Allow general framework use with AR

[letsbreelhere]

It'd be neat (e.g., for a Sinatra service I'm working on now) if Setler's generator script worked with any project that uses ActiveRecord, and not by requiring access to the Rails migration/generator libraries.

[letsbreelhere]

After taking a look this wouldn't need much at all; maybe this could be as easy as separating the migration piece into a Rake task.

[ckdake]

:+1: would merge