Added initgroups command, City/Multi-City Editors groups.
editors can now create, edit a subset of user fields.
better DRY for Group def'ns in initgroups command.
add a convenience Membership.city property.
in directory.admin, use membership.city property.
allow city editors to add/change membership role, org memb. types.
allow city editors to delete memb. roles, org memb. types.
don't let city editors change is_staff, it's useless by itself.
flatpages can now be edited by city/multi-city editors.
Merge branch 'master' into perms
Merge pull request #32 from toolness/perms

[WIP] Add "City Editors" and "Mutli-City Editors" staff groups.