A file named credentials.tf will need to be created that has the appropriate
provider credentials, for example:

variable "bluemix_api_key" {
   default = "blah"
}

variable "softlayer_username" {
   default = "blah"
}

variable "softlayer_api_key" {
   default = "blah"
}

variable "ssh_key" {
   default = "blah"
}