refs #409 - fix _ref=undefined bug caused by split('.', 1); also external API...

refs #409 - fix _ref=undefined bug caused by split('.', 1); also external API methods now expect seconds, and convert to milliseconds internally

git-svn-id: http://dev.piwik.org/svn/trunk@3846 59fd770c-687e-43c8-a1e3-f5a4ff64c105