Got rid of Maven Shade Plugin wherever it was possible.

Artefacts which still have need to use the plugin:

    - cucumber-groovy
    - cucumber-jython
    - cucumber-jruby

The PR is related to #518 and #520 issues.

Also, the `cucumber-core` artefact can't be used as standalone jar at the moment because of the `java.lang.NoClassDefFoundError: gherkin/util/FixJava`.
Maybe that would be appropriate to create something like `cucumber-standalone` artefact which has all needed shaded artefacts/jars.