allowed multiple select in membership app
updated invoices for membership applications
fix error for undeclared fields
merged with master
Merge branch 'refs/heads/master' into 443_multi_select_memberships

Conflicts:
	tendenci/addons/memberships/views.py
Merge branch 'master' into 443_multi_select_memberships. And added fixes
Merge branch 'master' into 443_multi_select_memberships. And updated migration file
Single invoice for multi-memberships
Some PEP8 on events/models.py
Setting activation date and expiration date when job invoice is paid or marked as paid.
PEP8 on job/views.py
PEP8 on jobs/models.py
Removing unused fields in memberships/admin.py
Disabling access to select user-defined fields that are already in use.
Add outstanding balance to admin list view for memberships.
Add choices attr to the invoice status_detail field so that it shows a drop down on model-report.
Disabling access to user defined fields in membership applications that are being used by "admin_only" as well as being "shown" on the membership application.
The event method that returns how many spots available now uses the "payment required" field in it's logic.  This feature was previously removed for an undocumented reason.
Merge branch 'refs/heads/443_multi_select_memberships'

Conflicts:
	tendenci/addons/memberships/views.py
Getting custom registration entry information using a more robust method.  This method will not break if custom registration information does not exist.