Added ability to remove unassigned user role.
Refactored code.
improve presentation of row data
catch protected errors when deleting line items (due to credit lines)
move SMS Billables report to the smsbillables app
Merge pull request #3331 from dimagi/sms_billables_report

Sms billables report
add SMS Gateway Fee Criteria report
add table headers
add rows
Merge pull request #3332 from dimagi/fix-invoice-trigger

catch protected errors when deleting line items (due to credit lines)
move SMS Gateway Fee Criteria interface to smsbillables
add filters to UI
apply filters
Merge pull request #3333 from dimagi/sms-gateway-report

Sms gateway report
add messages notice for trial subscriptions
add number of expected users and dimagi contact to pro bono form
Merge pull request #3334 from dimagi/pro-bono-updates

add number of expected users and dimagi contact to pro bono form
add trial notification to new domain email
update popup text for worker activity times report
Merge pull request #3336 from dimagi/update-worker-activity-popup

update popup text for worker activity times report