Fix lxc-info state regex for recent lxc versions

Recent versions of lxc-info (some pre-1.0 alpha or beta) use a different output format than prior versions (0.9).

Instead of

    state:RUNNING

the output is now

    State:          RUNNING

This patches adjusts the regex that parses this output to match both output formats and adds a unit test.

See the lxc code at https://github.com/lxc/lxc/blob/master/src/lxc/lxc_info.c#L303 for reference.