add option using utf8 to preg match strings

preg_match() should add 'u' option for using utf8 in especially double-byte language.

For example
English : `/^(?:|I )should be on "(?P<page>[^"]+)"$/`
Japanese `/^(?:|ユーザーが )(?P<page>[^\s]+) を表示していること$/`

In the case, partial byte of Japanese character( is not space ) may match space ([^\s]+) unexpectedly.