Add possibility to use Azure CosmosDb with ServiceStack OrmLite

[vgotra]

As CosmosDb is free service for MS Azure, it can be useful to have a possibility to use it with ServiceStack OrmLite

[mythz]

As CosmosDb isn't an RDBMS and there's no ADO.NET provider for it, OrmLite wont be able to support it.

Best we could do is create a typed library for it like we do for PocoDynamo for DynamoDb, but given there's already a decent .NET client for CosmosDB, creating and maintaining a new client wouldn't be a good use of our limited time.