Fix line endings issue of shell script files on Windows

Added section about setup on windows to README.md

Explained line ending issue in kibana/entrypoint.sh on windows.

Feature: how-to logstash plugin management

Installed and configured the logstash-filter-json filter for message parsing in JSON out of the box.

Close #49.

Fix error "[9] System error: not a directory"

When starting the stack `with docker-compose up`, it gives out the error:

```
ERROR: Cannot start container e032695b38cdcd1c72597004f2369a7127b8233c9ecc2320c3b2bbd10209654b: [9] System error: not a directory
```

kibana is now executed using exec

kibana should be executed with exec to give it pid 1 and bind signal forwarding with the container instance

Close #19

Close #18

Updated logstash configuration. The elasticsearch output is now directly connected to the elasticsearch container.