Integrated with new Homestead API; all tests passing
Add missing test
Adding format strings
Code review feedback - commenting and names
Fix up accidentally synchronous method
Update POST to have a blank body
Use PUT rather than POST for IRS/private ID association.
Minor fix to enure private ID is created before we associate a public ID
Make creating private ID a synchronous operation to avoid race conditions
Fix up conformity to API.
Avoid attempting to treat None as a string
Merge remote-tracking branch 'origin/new_homestead_api' into new_homestead_api
Improve error mesage when Ellis receives a badly-formed Location header from Homestead.
Merge branch 'new_homestead_api' of github.com:Metaswitch/ellis into new_homestead_api
Revert "Avoid attempting to treat None as a string"

This reverts commit b387a603213de259bb02f61863a454037abc5cd3.
Avoid race condition between adding public ID to a service profile and updating its iFCs.
Create iFCs as part of creating public ID; don't follow 303 responses or treat them as errors.
Fix up GET request for private IDs.
Use Location header correctly to build new URLs.
Use updated version of python-common