Creates a lxc-system-manage script for common operational tasks.

This creates a simple to use lxc-system-manage script that allows
the user to interact with some of the LXC internals that may need
to be adjusted and or recreated.
Merge pull request #440 from cloudnull/backport-proposed/juno-lxc-system-manage

Backport - proposed/juno - Creates a lxc-system-manage script for common operational tasks.