In Review Board 2.5, the datagrids were redesigned. However, this broke

the existing behaviour of the submitter column linking to the local site

user page when it was viewed under a local site. This patch fixes that

behaviour.

Tested this patch with a local site. Verified that the link in the

SubmitterColumn in the datagrid was to the user view on the local

  site.
Verified that the link goes to the global user view when not viewed on

  a local site.
Ran unit tests.