added support for updated and deleted sobject endpoints

Hello,

We found a need for the `updated` and `deleted` `SObject` endpoints so thought we would add them to this library. 
The API is documented in http://www.salesforce.com/us/developer/docs/api_rest/ under `REST API Reference / SObject Get Deleted` and `SObject Get Updated`. Example usages:
http://www.salesforce.com/us/developer/docs/api_rest/Content/dome_get_deleted.htm
http://www.salesforce.com/us/developer/docs/api_rest/Content/dome_get_updated.htm

I have added tests in the `connection.test.js` however I could not get the test suite to run properly. I could not get the tests to auth with Salesforce. I did create the `oauth` and `salesforce` `config` files. Also note that there is lag between updating or deleting sobject records and the actions being picked up and processed by internal Salesforce workers / queues and returned by the respective REST API. This is documented in the reference as well. That is why I do not test the actual content if the returned objects (ie check against the id's), just that the call worked and the basic structure of the result is correct.

I have tested inside my app with actual usage with good results.

Please review and provide feedback.

Thanks,

Bojan