fixes #355 - OO version of piwik.js which no longer modifies DOM;

remove misc/testJavascripTracker (interactive tests);
add tests/javascript (QUnit unit tests);
fixes #661 - use click event instead of mousedown;
fixes #549 - define your own download/outlink tracking classes;
fixes #82 - add hook interface for module


git-svn-id: http://dev.piwik.org/svn/trunk@1151 59fd770c-687e-43c8-a1e3-f5a4ff64c105