Update Packer dependencies, fix SSH and Softlayer issues and update README

[sytabaresa]

Hello, I'm using IBM Cloud Bluemix / Softlayer services and I want to collaborate to make this Packer builder more usable, I make a pull request with some fixes to the package and docs updates.

I found some issues:

• packer repo has changed and some inner packages are in diferent locations.
• dependencies aren't vendored.
• go ssh library is deprecated.
• softlayer APi add METADATA block devices that breaks the capture image script.
• README can be updated with some userful install information
• You can add IBM, Bluemix, Softlater tags to this repo to powers the metadata.

[sytabaresa]

this is my pull request #38

[guptamisha]

this is my pull request #38
Hi Sebastian,

I'm using IBM Cloud Bluemix / Softlayer services and created a packer with pull request 38 since i was facing METADATA block devices issue that breaks the capture image script. With this pull request, I am facing the issue in accessing ssh private key file, although Did not face this issue with leonidlm/packer-builder-softlayer.

Issue found is "when using base_image_id%!(PACKER_COMMA) you must specify ssh_private_key_file since automatic ssh key config for custom images isn't supported by SoftLayer API"
my Config json is like :

 {
    "type": "softlayer",
    "api_key": "",
    "username": "",
    "datacenter_name": "mel01",
    "base_image_id": "{{user `PVM_SLAYER_BASE_AMI_ID`}}",
    "image_name": "test-{{user `CURRENT_RELEASE`}}.{{user `BUILD_NUMBER`}}",
    "image_description": "test-{{user `CURRENT_RELEASE`}}.{{user `BUILD_NUMBER`}}",
    "image_type": "standard",
    "instance_name": "build-{{user `BUILD_NUMBER`}}-{{isotime}}",
    "instance_domain": "provisioning.com",
    "instance_cpu": 1,
    "instance_memory": 1024,
    "instance_network_speed": 10,
    "instance_disk_capacity": 25,
    "ssh_port": 22,
    "ssh_timeout": "15m",
    "instance_state_timeout": "25m",
    "ssh_private_key_file": "test.pem"
  }