Only map alias for documentation if required.
Don't rewrite envvars file if it already exists and not referring to separate envvars file.
Output envvars file and apachectl location if appropriate when setting up or running mod_wsgi express.
Fixes to output of envvars and apachectl for start-server.
Increment version to 4.2.2 and add release notes.
Merge branch 'release/4.2.2'