Allow passing constant values and environment variables

[weierophinney]

Some applications have configuration requirements that include constants and/or environment variables. It could be useful to allow passing values via CLI parameters so that these can be properly expanded during processing of the application for packaging.

As an example, GotCMS defines several constants that are then used in config/application.config.php; this would allow providing substitutions for them. (Currently, due to the fact that we include that file without first defining the constants, warnings are raised, and the config file in the package is malformed.)

The filters in zfcampus/zf-console#8 would be useful here, particularly QueryString and/or Json.

[weierophinney]

Ping @sophpie -- this is the other part of your report. :)