Busser Fixes

A number of fixes for `Kitchen::Busser` I wound while testing `1.0.0.rc.1` against a switch which runs a stripped down version of FreeBSD:

Fixes include:

* Busser config key name is `sudo` not `use_sudo`
* Ensure `busser/ruby_bindir` config value is respected
* Ensure `busser/busser_bin` config value is respected
* Remove all newline characters from remote Busser commands (see commit message for in depth explanation).

Here is the `.kitchen.yml` I used in my testing:
https://gist.github.com/schisamo/0b1eb8da5034f85199f0