Migrate the providers in the Pingdom terraform state file
Migrate the providers in the Pingdom terraform state file

Previously we issued the `terraform state replace-provider` command with
reference to the state file, but we didn't have a local copy of it.

Now we check if it exists, and if it does we
1. download it
2. migrate it
3. upload it

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf