Removed dependency on vertx-sync
Removed dependency on vertx-sync

logicus4078/vertx-jdbc-client,vert-x3/vertx-jdbc-client,ckaminski/vertx-jdbc-client,logicus4078/vertx-jdbc-client,logicus4078/vertx-jdbc-client,ckaminski/vertx-jdbc-client,ckaminski/vertx-jdbc-client