Add coll.indexPagesInRAM shell helper

DBCollection.prototype.indexPagesInRAM = function(name, opt) {

    var ns = this.getName() + ".$" + name;

    var cmd = { storageDetails: ns, analyze: 'pagesInRAM' };

    if (typeof(opt) == 'object') Object.extend(cmd, opt);

    return this._db.runCommand(cmd);

}