Update paas-billing to v0.52.0
Update paas-billing to v0.52.0

Changes:
* Wait between CF API calls if an error is encountered.
* Remove duplicated collection of services and service plans

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