Implements the support to register mobile devices as clients on REST-Like API bus.
NO_USER
BY_LOGIN
BY_MAIL
BY_ID
$active :
isActive()
register( $name, $user = FALSE)
unregister( $id, $user = FALSE)
randomPrivateKey()
validatePrivateKey( $pk)
formatPrivateKey( $pk)
getRegisteredDevice( $id)
registerDeviceAccess( $id)
registerGoogleCloudMessage( $id, $gcm)
sendNotification( $apiKey, $ids, $message)