security step 1: https server (no client certificates), basic
authentication (without user check)

added keystore for HTTPS testing
basic plaintext user store with initialisation method
a first account can be created by using command line parameter
--init-user-store

authentication not implemented yet
UserStore.setPassword(...) with RandomAccessFile
use RandomAccessFile in user store initialisation
password check implemented
prepared ResourceAuthFilter for password check
open todo: find user in UserStore
Loading users from user store to internal cache in UserStore
security step 1: basic authentication via user store enabled (plaintext
passwords only at the moment)