Adding support for user locking

* Currently no GUI, use DB access to change the row entry
* Upgraded Database table `accounts` with upgrade SQL
* Updated `admin` field to `is_admin` as boolean
* Modified pages, classes, templates to support is_admin and is_locked

Addresses #147
Add admin/lock changes to admin panel

* Add clickable boxes for Admin and Locked status for all users
* Change status via Ajax call, script embedded to the admin page

Fixes #147
Merge pull request #174 from TheSerapher/issue-147

Issue 147