Jail work and fixes

- sipcalc can be used as an integer

- warden python class has bspkgng now, along with some bugfixes for the
  new bit flags from all the warden changes.

- flag pluginjail's as vanilla by default since no new packages need to
  be installed in them.

- jail create form has been updated with the option to configured a
  bridge ip. It's hidden in the advanced field and automagically
  assigned the same way the jail is if a jail network is configured.

- nanobsd build has been updated to install a pluginjail package list
  file into the warden directory so the warden can use it to install
  packages into the pluginjail world chroot.

- Removed the need to upload or download a pbi jail for plugin jails.
  Now a stock freebsd jail is used, cloned to a pluginjail root,
  bootstraps pkgng and installs the packages necessary needed by a
  plugin jail, then snapshots it. When pluginjail's are created, a new
  clone is made of the base pluginjail snapshot.

- Added checks when configuring the vimage bridge interface that if the
  same ip address is going to be configured then it's skipped.

- Added ability to warden.conf to specify FREEBSD_RELEASE so that the
  warden can fake what version of FreeBSD it's using. This helps when
  downloading packages and jails.