Add conductor environment during build

[chouseknecht]

ISSUE TYPE

• New feature

SUMMARY

Closes #566

Adds conductor environment variables defined in container.yml to the conductor image. Given the following in container.yml:

version: "2"
settings:

  conductor:
    base: centos:7
    environment:
      http_proxy: http://my.proxy.server:8000
      https_proxy: https://my.proxy.server:84300

  project_name: tstenv

The following ENV statements get added to the build Dockerfile:

Step 1/14 : FROM centos:7
 ---> 328edcd84f1b
Step 2/14 : ENV ANSIBLE_CONTAINER 1
 ---> Using cache
 ---> 2066daf83ee0
Step 3/14 : ENV http_proxy http://my.proxy.server:8000
 ---> Running in 9a36c1421e69
 ---> 892f46c876ef
Removing intermediate container 9a36c1421e69
Step 4/14 : ENV https_proxy https://my.proxy.server:84300
 ---> Running in 707d5fa56a08
 ---> 249df1272120