Add support for environment variables

[smalot]

Hi,

In webserver context, environment variable are often skipped or wrong, because forced by the webserver process itself. So it's necessary to prefix any executed command line by a set of environment variable assignments.

eg: the environment variable 'HOME' is missing when php is run under Apache.

A function like addEnvironmentVariable('HOME', '/home/username') could prefix any command line with:

$> HOME="/home/username" ....

So, could you add this support ?

Many thanks