remove copyright boilerplate from .pp files?

[jhoblitt]

A few of the .pp files have APL2 copyright boilerplate in them, which seems unnecessary since the entire module is under APL2.

manifests/credentials.pp
1:# Copyright 2014 RetailMeNot, Inc.

manifests/security.pp
1:# Copyright 2014 RetailMeNot, Inc.

manifests/slave.pp
109:# === Copyright
111:# Copyright 2013 Matthew Barr , but can be used for anything by anyone..

manifests/user.pp
1:# Copyright 2014 RetailMeNot, Inc.

@mwedgwood-rmn @matthewbarr - do you have any any objection to moving your copyright mark into LICENSE and stripping the boilerplate?