Update Restund HTTP authentication to cope with new Homestead API
Merge remote-tracking branch 'origin/dev_new_homestead_api' into dev_new_homestead_api
Restore commented-out function to get the private ID; add a UT that includes a real Authorization header
Code review markups
Merge remote-tracking branch 'origin/dev_new_homestead_api' into private_id

Conflicts:
	sprout/registrar.cpp
Merge pull request #233 from Metaswitch/private_id

{Reviewer: Matt} Pass private ID to Homestead correctly, restund auth