Add support for matchPattern:options:

This commit enhances the KWRegularExpressionPatternMatcher class to support specifying NSRegularExpressionOptions in an expectation.  For example:

    it(@"succeeds with NSRegularExpressionCaseInsensitive option", ^{
        [[@"abABab" should] matchPattern:@"(ab)+" options:NSRegularExpressionCaseInsensitive];
    });

    it(@"fails with non-matching NSRegularExpressionCaseInsensitive option", ^{
        [[@"abABab" shouldNot] matchPattern:@"(abc)+" options:NSRegularExpressionCaseInsensitive];
    });