<fix>[conf]: Specify the Python virtual environment as python2.7
<fix>[conf]: Specify the Python virtual environment as python2.7

Resolves: ZHCI-816

Change-Id: I6664737369726b6b716161717476757a6e707164

AlanJager/zstack,zstackio/zstack,AlanJager/zstack,MatheMatrix/zstack,AlanJager/zstack,MatheMatrix/zstack,zstackio/zstack,zstackio/zstack,MatheMatrix/zstack