Add skeleton for device provisioning.
Implement device model management.
Check for read_only flag when editing contact.
Group device overview.
Implement device firmware management.
Implement device config management.
Implement device profile management.
Add device management to top menu.
Reset DT field id if it's not selected.
Add front and mac image for devices.
HTML-escape DT fields before displaying it.
Fix registration list if ignore_auth_realm is set.
Make domain optional when handling reg contacts.
Render empty string on null values.
Add PBX device skeleton.
Implement PBX field device handling.
Implement PBX field device config delivery.

Currently supports sip.username, sip.domain and sip.password tags,
more to come.
Implement PBX device boot-strapping.
Add display name to PBX device config template.