Create/Update API support

Ability to create/update select resources. Routes below.

location_machine_xrefs:
(POST)/api/v1/location_machine_xrefs(.:format)=>api/v1/location_machine_xrefs#create
(PUT)/api/v1/location_machine_xrefs/:id(.:format)=>api/v1/location_machine_xrefs#update

locations
(PUT) /api/v1/locations/:id(.:format)=>api/v1/locations#update

machines
(POST)/api/v1/machines(.:format)=>api/v1/machines#create