Add error catching on stats script
impliment open membership-requesting
Remove sign in banner
Merge pull request #852 from loomio/request-membership

Request membership
Merge branch 'master' of github.com:loomio/loomio into feature/change-comments-from-polymorphic-to-normal

Conflicts:
	app/controllers/groups/memberships_controller.rb
	app/models/ability.rb
	spec/models/ability_spec.rb
	spec/models/group_spec.rb
	spec/models/user_spec.rb