List users by apps they have signin permission for

The signin permission was a fake boolean field which gets removed and injected into the permissions array, having the value just in the array makes it hard to filter by, so by duplicating the data in a boolean we can filter the users who have signin permission.

Uses ransack to handle searching, and updated the existing search.

Does not delete the signin_permission param after submitting the user permission form, so it set as a boolean.

The motivation for this is to allow admins to filter user by application to see who has access to what.

Adds a rake task to clean up the data so we can query the signon property

    bundle exec rake users:fix_signin

![screen shot 2013-09-19 at 22 28 36](https://f.cloud.github.com/assets/215/1176850/d947346e-2172-11e3-8a66-54838e4155dc.png)