Added ability to specify the Azure Table Storage Table name

This was flagged as a todo in the code but was apparently not implemented due to some performance problems with using a table name that is different from the entity name. The only docs I could find on this were [here](http://social.msdn.microsoft.com/Forums/windowsazure/en-US/d84ba34b-b0e0-4961-a167-bbe7618beb83/net-and-adonet-data-service-performance-tips-for-windows-azure-tables?forum=windowsazuredata) which is from 2009 and (from what I can tell) is specific to querying. I'm not sure if this is actually still an issue. Anyway, I've put a note in the comments that it might impact performance.

If you don't specify the table name, the behaviour remains unchanged.