DevOps: Create script to reproduce environment for using VMware vCenter and NSX

Create a script env_assist.py for revert environment (including VMware vCenter and NSX nodes) before system test. It must works in such manners:

1. there is /etc/env_assist.json file in each nodes where we want to launch env_asist. Each of our environments must be described in this file. For example:
{"env_Ubuntu_vcenter_ha": {"env-name": "env_Ubuntu_vcenter_ha", "nsxbr": {"ip": "172.16.0.1", "br": ""}, "snp": {"q": ["qemu:///system", 3, "ready_with_3_slaves"], "vb": [["<email address hidden>", "vcenter", "vcentersnap"], ["<email address hidden>", "nsx", "nsxsnap"]]}, "vlanifs": ["eth1.851", "eth1.852"], "br_private": "private", "br_public": "public"},
"env_Ubuntu_vcenter_simple": {"env-name": "env_Ubuntu_vcenter_simple", "nsxbr": {"ip": "172.16.0.1", "br": ""}, "snp": {"q": ["qemu:///system", 3, "ready_with_3_slaves"], "vb": [["<email address hidden>", "vcenter", "vcentersnap"], ["<email address hidden>", "nsx", "nsxsnap"]]}, "vlanifs": ["eth1.853", "eth1.854"], "br_private": "private", "br_public": "public"}}

2. script provide the decorator with_env, which take a environment as a parameter and revert it around tests. Tests must be defined with it:
@with_env
def test(env):
    ...
    ...
and launched with environment-argument:
env = getenv()
test(env)

3. name of the environment could be passed by environment variable from jobs or as command line argument or any another way if we use this script as pythonic library.