Get OS_ env vars via os.environ
Get OS_ env vars via os.environ

It simply avoids executing env and grep.

JIRA: FUNCTEST-271

Change-Id: If71aeb9c7b10df5dca54ca9cbc35ba5e6b5ebef4
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

opnfv/functest,mywulin/functest,opnfv/functest,mywulin/functest