add test cluster configs for 2.0, 2.2, 2.4, and update 2.6
chmod +x devel/bin/harness.pl
add test coverage target to generated Makefile
make orchestration test libraries a bit less verbose
move server-attribute checks into the connect method

Because a multiple seed list creates MongoClients without connecting,
they get the default max_bson_size, not one from the server.  This
commit ensures that max_bson_size is updated and the wire protocol
version is checked on every connect.