gitweb: prefer gitweb.owner over project list
When showing the summary page, the current owner displayed should
be taken directly from the current value in the config file, not
from a possibly outdated value in the project list.
Make git_get_project_owner prefer the value of gitweb.owner if
it exists when fetching the owner for the current project but
retain the current order (project list value first) if there
is no project (i.e. project list page) or the project being
fetched is not the current one.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>