Even more search improvements - 2nd attempt :)

- I moved search button to the top,
- added bigger More button,
- did some cleaning (removed unused code),
- replaced search POST request with GET request: search url gets updated and can be bookmarked,
- fixed pagination (no more custom endless js needed) and moved the text displaying number of results,
- introduced history.js due to IE issues (https://github.com/browserstate/history.js),
- replaced search parameter with q, so it is consistent with clickable searchable tags.

Sorry about creating a second PR, but the first one was a mess. @gandalfar please take a look at this one.