Support sharding in test suite getServerVersion() function
Fix version checking bugs and inconsistencies in test util includes

mongos.inc was comparing the server version and $needs version backwards. Additionally, it was only checking the standalone server version.

replicaset.inc and standalone.inc were defaulting to ">", instead of ">=".

unix-standalone.inc was ignoring $needsOp and always performing a "<" comparison.
Merge pull request #615