Replaces old Master / Slave stuff with a simple connection setup

[tonymillion]

You can now setup connections to replica sets like:

    $connection = new Shanty_Mongo_Connection("mongodb://user:password@db.yourserver.com:27017");

    $connection->setSlaveOkay(true);    // optional to offload reads to slaves

    Shanty_Mongo::addConnection($connection);

as per the php-mongo docs your connection string can look like "mongodb://db1.example.net,db2.example.net:2500/?replicaSet=test" or you can pass the replica set in as an array in a second param!

addConnection optionally takes a connection group just like the old stuff!

This fixes the problem with replica set connections I saw previously.

[coen-hyde]

Hey Tony,

Thanks for the pull request. This makes a lot of sense. There's no need for the master/slave stuff. Two things we need to do before we can merge this:

• Merge current master with this
• Update the tests. (should be reasonably easy, we'll just delete a bunch of tests :) )

Can I suggest you create a separate branch from commit ad2dc97 and merge my master then create a pull request for that.

Cheers, Coen