use objectset for group model

use django_tables2 for table views
update connection param

add useless search box and useful add button
add slug field to groups
add group messaging

update group form
pass recipients as list instead of set
add select2 to group edit interface
initial user to user messaging
add comment
add recipient count to groupmessage model
add groupmessage listing

add group message sending
add requirements file, update setup.py
add phonenumbers to requirements
remove last bit of old contact extension
update tests

remove unused code and stale tests
allow multiple countries for phone normalization
update README