Support creation of accounts via REST

PUT on '/accounts/<username>' creates a new account.
The code from the 'create-account' SSH command was moved to the REST
layer.

Change-Id: Ic8fd9daf9fb64f7918b7f7eb461f8e8e957099a9
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
6 files changed