support to specify a non-matching pattern with '!' character (exclamation mark).

Now, You can prefix the pattern string with a '!' to specify a non-matching pattern.
e.g. http://stackoverflow.com/questions/5352249/rewrite-rule-if-condition-is-not-matched

Thank you for suggestion by m.yuzuki (@ephemeralsnow)
https://twitter.com/ephemeralsnow/status/347983380396244992