Add ua_ver and mshtml_build requirements

This vulnerability is specific to certain builds of IE9.
Add a comment about what this build version range is covering
Use BrowserExploitServer mixin for ie_setmousecapture_uaf.rb
Land #3140, @wchen-r7's requirements for ms14_012_textrange
Land #3143, @wchen-r7's switch to BrowserExploitServer on ie_setmousecapture_uaf