Create default permission groups

[zsol]

Permission groups are handled by sfGuard and should be set up in fixtures

[zsol]

some ideas for groups:

• replay administration
• comment administration

[zsol]

This is done. Three permissions as of now:

• ReplayAdmin -> allows access to the replay administration backend
• CommentAdmin -> allows access to comment admin
• AdminAdmin -> allows access to all admins

There also are associated groups created in fixtures.