Allow getting raw data from Gremlin.Net.Driver.IGremlinClient

I am developing an ORM-style server driver for Gremlin. To communicate with Gremlin-servers, I rely on Gremlin.net.

Since ExRam.Gremlinq deals with deserializing Json data to POCOs by itself, it needs to get raw data from an IGremlinClient. Currently, it's only safe to use SubmitAsync<T> with object or dynamic as T, or other (scalar) types if known it advance. To get a raw JToken, I currently use a hack.

The hack is not only ugly, it prohibits users of ExRam.Gremlinq to create and pass in instances of IGremlinClient by themselves, which could become necessary e.g. for adjusting the Graphson version etc.

I had a look into the sources of Gremlin.net. It deserializes a server's answer to a ResponseMessage<JToken>, so the JToken is available in any case. It would be a trivial change to check the type parameter T and return the token if typeof(T) == typeof(JToken), and I could definitely file the PR for that. However, I'm of course less aware of possible unintended implications. Any thoughts are appreciated!

thx