SourceForge.getRemoteProduct() should return a string, not a tuple

At the moment SouceForget.getRemoteProduct() returns a tuple of of (group_id, atid). Similarly, BugTracker.getBugFilingandSearchLinks() expects a tuple for SourceForge bug trackers.

The problem is that we store remote_products as strings in the DB. Having to care about converting from tuples to strings and back again is a PITA, so for the sake of simplicity we should store 'group_id&atid' for SourceForge. Only getRemoteProduct() (which returns this in the first place) and getBugFilingAndSearchLinks() (which needs to parse it) need to care about this.