Added no_trailing_whitespace.allowed_in_comments rule option. fixes clutchski/coffeelint#45

I don't think most projects use markdown or docco in comments, so this
rule is off by default (backward compatible).
Added an exception to exclude errors caused by long URLS in comments.
Merge branch 'line-length-exception' into installable
Merge branch 'trailing-space-45' into installable
New build