Register init

Calling the init endpoint starts a new registration and returns data to be fed to the authenticator.

Request

Method	Path	Content-type	Body
POST	/register/init	application/json	A `RegisterInitRequest` data object

Code	Content-type	Body
200	application/json	A `SignedResponse` enclosing a `BlisacheResponse`<`RegisterInitResponse`>
400	application/json	A `SignedResponse` enclosing a `BlisacheErrorResponse` signaling an error in the input data
422	application/json	A `SignedResponse` enclosing a `BlisacheErrorResponse` signaling a functional error
500	application/json	A `SignedResponse` enclosing a `BlisacheErrorResponse` signaling an internal server error