http refresh tag is supported.

E.g., test/page1.html -> test/page2.html -> test/page3.html,
where page2.html is
        <meta http-equiv="refresh" content="0; url=/test/page3.html">
now ctAjaxify will detect the meta refresh tag, extract the destination, and
do not cause a page fresh. And also do not cause forward/back issues.
Merge pull request #5 from liyu1981/master

http refresh tag is supported。