added spent_for_group method on membership to keep track how much each person has contributed to his/her group
added color changes and view changes for owes and owed values. add view changes that will change on viewing a purchase if it is your purchase or another member of your group's purchase.
added the ability for a user to remove him/herself from a group, changed the root path so that if a user removes him/herself from all groups it will redirect the user to create a new group
changed application layout column width.
attempting to get payment ot work
removed settle button from view
removed settled at on purchase show
fixed member owed display, added dependent destroy to users memberships and purchases