Fix API project lookups when querying with a namespace with dots
Attempting to use the /projects/:id
API in the namespace/project format
would always result in a 404 if the namespace contained a dot.
The reason? From http://guides.rubyonrails.org/routing.html#specifying-constraints:
"By default the :id parameter doesn't accept dots - this is because the dot is
used as a separator for formatted routes. If you need to use a dot within an
:id add a constraint which overrides this - for example id: /[^\/]+/
allows
anything except a slash."