New install always reports failure

A new install off of dev branch will always report it has failed.

This is because forward.install used to store the CREATE TABLE query results in $query, and then check for $query's existence to see if the installation succeeded. When forward_statistics was added, the '$query = db_query(...' line was changed to simply 'db_query(...', but the check to see if $query existed was left in.

Patch for forward.install enclosed. I really don't know that the check is actually necessary, as IIRC if the table insert fails Drupal will throw a logged warning anyway so this just seems to duplicate functionality. But just to leave the code closer to how it originally worked, I left the check in. It can trivially be removed later if that's deemed appropriate.