Metadata service update for VPC - EUCA-9951

The metadata service now allows the instance to be specifed via an HTTP
header instead of being derived from the remote IP.

EUCA-9951
updates to config/metadata handling
Merge branch 'testing' into team/network/vpc-mido
new meta tap method
Merge branch 'dev/sjones/EUCA-9951' into team/network/vpc-mido
latest meta-taps and nginx proxy setup
better cleanup handling for meta taps and adding nginx_proxy.conf to install
latest merge from testing
indent
indent and null vpc check for proxy teardown
Merge branch 'team/network/vpc-mido' into testing