Write a section that introduces available TinkerPop support for different programming languages

[krlawrence]

As well as adding some detailed coverage of using the GLV clients (covered by other issues) an introductory section is needed that introduces the various support available for users of different programming languages when working with TinkerPop and Gremlin and Gremlin Server.

The coverage should include:

• Java (local Tinkergraph and GLV support)
• Groovy (local TinkerGraph and GLV support)
• Python (GLV only unless Jython is used but Jython approach seems unreliable)
• C# (GLV only)
• JavaScript (GLV only)
• Go - Various open source options but with limitations new Gremlin Go client.
• Ruby (has to use HTTP/JSON) I could not get JRuby/TinkerGraph to work (so far) there is now a Ruby client in open source.
• Rust - now has a fairly complete open source client

[krlawrence]

Added a sample (glv-client.js) showing a simple Node.js gremlin GLV client #107