[google] Add support for network and external_ip

 * Add support for an other network than default
   ("default" network is still default network)
 * Can specify if creation or not of an external_ip
   (External_ip is still created by default)
[google-compute-engine] Add private_ip_address method for server
Merge branch 'new-network' of https://github.com/rvrignaud/fog into rvrignaud-new-network
[google] Add support for network and external_ip

 * Add support for an other network than default
   ("default" network is still default network)
 * Can specify if creation or not of an external_ip
   (External_ip is still created by default)
 * Add private_ip_address method for server
 * Add example for vm creation with network
Merge branch 'new-network' of https://github.com/rvrignaud/fog into rvrignaud-new-network
Examples tweak
remove networks
Merge branch 'master' into new-network
[google|compute] better check on server.public_ip_address
Merge pull request #2009 from rvrignaud/new-network

[google|compute] Add support for network and external_ip during server creation