Fixes #2902

 * removed ip_address_pre_mask_length setting -- now there is only one setting which anonymises after testing for IP exclusion
  * Reverted the "synchronize" from [5772] since not needed anymore
 * Added integration test to test that IP is indeed anonymized 
 * Added integration test to test that IP is anonymized AFTER testing for ip exclusion 


git-svn-id: http://dev.piwik.org/svn/trunk@5776 59fd770c-687e-43c8-a1e3-f5a4ff64c105