Fixes #1351 All error messages displayed to screen/API should not be translated. Thanks JulienM for patch!

I simply refactored the 'you must be have %s access [...]' messages by putting the admin/view/superuser as a parameter in the string

git-svn-id: http://dev.piwik.org/svn/trunk@2246 59fd770c-687e-43c8-a1e3-f5a4ff64c105