Add mod-mongo-persistor 2.1.1
$ vertx install io.vertx~mod-mongo-persistor~2.1.1
Attempting to install module io.vertx~mod-mongo-persistor~2.1.1 
Downloading io.vertx~mod-mongo-persistor~2.1.1. Please wait... 
Downloading 100%
Module io.vertx~mod-mongo-persistor~2.1.1 successfully installed 
Succeeded in installing module