Pass launch metadata as enviroment variables
Pass launch metadata as enviroment variables

The launch metadata is provided with 'nova boot' and
serves effectively to pass varibles into an instance. This
runtime key-value pairing seems to map cleanly to environment
variables as used by Docker. Use of environment variables
is highly desired amongst nova-docker users and this seems to
be the cleanest solution to deliver this feature.

Co-Authored-By: Davanum Srinivas <c55924fd2fe0c2298c08b526e02fbe532468f547@linux.vnet.ibm.com>
Change-Id: I0292bf065191c6a188e39a7d2f2c0a5057ec67f5

Ye-Yong-Chi/nova-docker,thanhtien522/nova-docker,stackforge/nova-docker,gwdg/nova-docker,AlphaStaxLLC/nova-docker,Juniper/nova-docker,mangalaman93/nova-docker,AlphaStaxLLC/nova-docker,gwdg/nova-docker,Juniper/nova-docker,godvmxi/nova-docker,devdattakulkarni/nova-docker-1,MinmingQian/nova-docker,cloudbase/nova-docker,Ye-Yong-Chi/nova-docker,msrba/nova-docker,msrba/nova-docker,devdattakulkarni/nova-docker-1,mangalaman93/nova-docker,ggiamarchi/nova-docker,MinmingQian/nova-docker,thanhtien522/nova-docker,godvmxi/nova-docker,cloudbase/nova-docker,stackforge/nova-docker,ggiamarchi/nova-docker