cpi should provision ssh keys

[cloudfoundry-community]

cpi should provision ssh keys

[poblin-orange]

WIP
the cpi now creates the vm with the ssh keypair (ssh keypair creation with cloudstack API is now a prerequisite).

The ssh key is accessible from
curl -X GET /latest/meta-data/public-keys
KO from bosh-agent expected url
get http://VROUTER_IP/latest/meta-data/public-keys/0/openssh-key

[poblin-orange]

should leverage the feature provided by this PR, when merged
cloudfoundry/bosh-agent#71

[poblin-orange]

leveraged the new properties in agent.json

  "Infrastructure": {
    "Settings": {
      "Sources": [
        {
          "Type": "HTTP",
          "URI": "http://169.254.169.254",
          "UserDataPath": "/latest/user-data",
          "InstanceIDPath": "/latest/meta-data/instance-id",
          "SSHKeysPath": "/latest/meta-data/public-keys"

        }

bosh-agent should be able to provision ssh public key as set by CPI, for stemcell > 3615.