DTACLOUD-416 Openstack driver, Avoid base64 encoding the user data

[jvlcek]

Problem:
  The openstack driver had been base64 encoding the user data
  resulting in inconsistent behavior between drivers.

Solution:
  Do not base64 encode the user data in the Openstack driver.

Testing:
  I tested by curling http and also using the ruby client to
  create instences with user data on Openstack, RHEVm3.1 and Ec2

  The test matrix:

  rhevm3.1

    ruby( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
Base64 encoded )
    curl( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
decoded/readable )

  ec2

    ruby( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
Base64 encoded)
    curl( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
decoded/readable )

  Openstack

    ruby( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
"Double" Base64 encoded )
    curl( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
Base64 encoded )

  Openstack (with this patch)

    ruby( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
Base64 encoded)
    curl( Base64 encoded user-data sent) -> instance has ( user-data rcvd 
decoded/readable )