Add comment for syntastic options
Work around syntastic setting LC_ALL=C for checks

This causes 'puppet parser validate' and puppet-lint to complain if a
manifest include Unicode chars.

https://github.com/scrooloose/syntastic/commit/9b698bb32be7742e8846bb2419ccf2bc73647361
https://github.com/scrooloose/syntastic/issues/665