Starting to add support for migrations in plugins
Adding ability to migrate up in plugins
Adding plugin support to the rest of the commands.
Using a seprate phinxlog table for each plugin

The reason for having a separate table is that otherwise, when executing
the status command, migrations for other places will be reported as missing
which looks like an error instead of the intended behavior.
Merge branch 'master' of git://github.com/lorenzo/cakephp-migrations