Escape user names.

[y120]

Fixes #13

[coveralls]

Coverage increased (+0.05%) to 83.819% when pulling c75b65c on y120:master into c631b40 on magicmark:master.

[magicmark]

Thanks for the PR!

Until https://github.com/benjamingr/RegExp.escape is a thing, would something like https://github.com/sindresorhus/escape-string-regexp work instead? then we could avoid adding our own escaping logic