start using ngcp-schema (for domains)

- requires: ngcp-schema and sipwise-base
restore confirmation dialog on delete button

- as it was in rev. e7cafadcc3d55962427d18f047e1d14f1f409bb5 (for example)
simple edit, create, delete for domains

- does not use the dedicated methods in NGCP::Schema::billing
outsource model config to config file
change data handling in ajax method

- resultset is now processed directly by ajax method
- small fix in config file
fix/restructure domain controller to use resultset more consistently
use resultset for searching, sorting and pagination

- also for rowcount
- also do some cleanup/coding style
domain controller: error message, some simplifications

its possible to use resultset in base chain now,
but that will change when we use the convenience methods in the schema
domain: use create_domain() from ngcp-schema to create domain
domain: remove edit button, add preferences link
have a Preferences Form (extending FormHandler)
make preferences table

but keep preference form for now
domain preferences: fix form, create overlay
Properly display domain preferences in full list.
Improve visual layout of preference list.
Disable drop-downs in preference list.
Implement first part of editing domain preferences.

Show form accordig to preference type. Still doesn't save
correctly and lacks support for max_occur=0 cases (e.g.
lists of strings).
Clean up Settings menu for admin.
Some more fix attempts for dom-prefs, WIP.
Fix prefill and update of preferences.