Add environement target in image name

Image name were named exactly the same no matter which
environement/section we were running.

We now have :

_dox/$project_name_$environment_(base|test)

as image name, the _dox and not dox is cause docker wants a namespace
with at least three chars.

Change-Id: I3ea05c0907fb911aaca96a18215c5a44ce2a6ebc