BUGFIX: add go.mod, go.sum; fix cli dependency

[FIX] Update mainscript for usage with actual cli-Version

TASK: Add options summary and fix typo

TASK: Support Windows

TASK: Add a detailed documentation on how to run the flow-debugproxy in docker containers

Fix incomplete data from xdebug

TASK: Update Dockerfile

Closes #33

Due to the usage of absolute paths in the source, the application code should be put into go/src/ folder to prevent downloading of the source from github.

Using new build method as described in https://hub.docker.com/_/golang/

Add support for sub contexts

Adds support for path mapping while using sub context.

`./flow-debugproxy -c "Development/Local"`

Fixes #3