Cukes properties should be overridden by environment variables or else

[berndgoetz]

I should be able to override Cukes properties via environment variables, or on the command line - that enables to leave property files untouched, e.g. for user id and passwords. Otherwise they must be put into those files and the risk to commit secrets increases.

Alternatively, an overriding ".env" file should be supported by Cukes. That file would by default be excluded from Git commit.