Start of bugfixing for SAAS-349.

* Also identity verification for erry on Freenode.
Freenode identity verification for #airtime
Fix SAAS-349 by preventing password changes in demo mode.

* Added a NotDemoValidate validator class to ensure no changes to a field in demo mode.
* Prevent the user from changing the password of any user in demo mode.
* Fixes SAAS-349.
Merge branch '2.5.x' of dev.sourcefabric.org:airtime into 2.5.x