Updated Products.Reportek with the following changes:

- Minor changes to ReportekUtilities.
- Added statistics and envelopes.autocomplete browser pages in
  views.zcml.
- Changed assign_role functionality to add the new role instead of
  overwriting existing ones.
- Changed revoke_roles functionality to add the possibility of individually
  select which roles to revoke.
- Added functional tests for ReportekUtilities