Allow html generation only with the concordion md to html translator

[vgheo]

As a quick validation of the MD with concordion semantics, allow the user to to generate the html file with the concordion translator.
The user could inspect this file in the browser - without having to wait for the full test execution.

As UI - this could be achieved as an option of the Concordion Run Configuration.
( eg "html generation only")

[vgheo]

This is a lighter alternative to #17