* Fixing broken POST tracking requests

 * Now displaying gif after init, so that errors can be displayed properly when occuring during a BULK import 
 * Fixes #3270 Displaying plain errors when the Tracking request is authenticated (ie. when runnning log import or other manual tracking API calls)

git-svn-id: http://dev.piwik.org/svn/trunk@6642 59fd770c-687e-43c8-a1e3-f5a4ff64c105