Added options argument to .html() static method.
Be more strict with object check.
Implement `Cheerio#add`
Made it less insane.
Merge pull request #502 from jugglinmike/add-add

Implement `Cheerio#add`
Merge pull request #503 from alexindigo/master

Added options argument to .html() static method.
Options are passed from element html method to static one