Add 9.2-RELEASE jails to upcoming 9.2.0 release

- Rename existing warden templates for pre-9.2.0 jails to appropriate
  version
- Add get_avatar_conf() function to common/system.py
- Add warden functions to determine FreeBSD version and architecture for
  templates
- Bugfix for get_jails_index(), use 'x86' instead of 'x32'