The previously hardcoded lxc path prevented the sudo wrapper from
working in environment with alternative `lxcpath`.
I had to move `sudo_wrapper` from `provider` to `LXC` because the
concept of "provider" is tied to a machine when a command sush as
`sudoers` is not.
Fixes#413 and #399
Previously, we hardcoded to using the ruby binary in /opt/vagrant[..].
On some systems, this path is incorrect, so instead we use the
path of the interpreter that is executing the `vagrant lxc sudoers`
command.
I ran into an issue locally where I didnt have lxc installed and some
commands were giving me back some false positives. Weird but this fixes
the problem I was facing.
