Add support for global notification flag as well as expiration dates.
Merge pull request #1 from ging/master

Merge master in before issuing pull request.
notifications, not notification.
Merge pull request #134 from mikesnare/master

Global notifications and expirations.
Add lambda call to scopes
Merge pull request #135 from ArmandoMendoza/master

Add lambda call to scopes.
Ignore public/uploads/tmp path
expired? shouldn't puke when expires is nil

As described
Merge pull request #137 from mikesnare/master

notification.expired? shouldn't puke when expires is nil
Merge remote-tracking branch 'upstream/master'

Conflicts:
	app/models/receipt.rb