Added crossdock integration tests

[Falco20019]

Which problem is this PR solving?

• Addresses #85
• Follow-up #152

Limitations

We sadly still can not create Linux images from AppVeyor, but at least we want to add the code and be locally able to test it.

Short description of the changes

• Added crossdock support to jaeger-client-csharp
• Testing against csharp, go, java and python

[Falco20019]

@saschaholesch I would like to have a look with you together over the integration.