To avoid having to use OCP\Appframework\Http\Http in the public - and stable
- API OCP\Appframework\Http is now both a class and a namespace.

It doesn't make sense for subclasses to have to implement
all methods.

Now only non-parable PUT requests return a stream resource.

It's easier to find errors in the code if an exception is thrown.

It's easier to find errors in the code if an exception is thrown.

It's easier to find errors in the code if an exception is thrown.

@PublicPage - No user logon is expected
@NoAdminRequired - the login user requires no admin rights
@NoCSRFRequired - the incoming request will not check for CSRF token