Releases for Organic groups defaults

Fixed:

- Bug #1031994 by capellic: Fixes broken 'if' statements for overriding membership requests.
- Issue #1123524 by Patrizio, KaleWorsley: Allow admins to restrict the available membership request options for a group type.
- Allow admins to check the public checkbox by default on specific group post types for a specific group type.
- Issue #1085532 by capellic: Bug - Null values being interpreted as 0.