Adds creator_id to groups
Ability to change group time restricted to group creator
Creating a new group now done asynchronously on submit button click
Some small changes to styling of current member group update form
Merge pull request #2 from bajh/group-times

Group times
Adds Invitation Mailer class and invitation form to groups page
Mailer is working
Routing to join community from email
Authorization control for users accepting email invitations