[CLEANUP] Admin Checks

* [REMOVED] SQL Checks, those won't be done since we need SQL to
  login as admin anyway. Are handled in database.inc.php too.
* [CHANGE] Dropped *nix detection since it would not detect Linux PHP_OS
* [IMPROVED] Simply check if we can use socket_create at all, fall back
  to fsockopen if this does not exist.

Not addressing any specific issue, just some cleanup.