title: Create databases with liquibase on empty mysql instance
body: <p>I have fresh mysql instance and want to be able to create a plenty of databases and populate it with liquibase.
  While I have scripts (changesets) which works fine on manually created databases I want to be able to create databases with liquibase as well.
  When I try to connect without specifing database in URL I've got the error:</p>
  
  <pre><code>liquibase --driver=com.mysql.jdbc.Driver --url=jdbc:mysql://localhost:3306/ --username=root --password=admin --changeLogFile=create_dbs.sql tag empty
  Unexpected error running Liquibase: Incorrect database name '' [Failed SQL: CREATE TABLE ``.DATABASECHANGELOGLOCK (ID INT NOT NULL, LOCKED BIT(1) NOT NULL, LOCKGRANTED datetime NULL, LOCKEDBY VARCHAR(255) NULL, CONSTRAINT PK_DATABASECHANGELOGLOCK PRIMARY KEY (ID))]
  </code></pre>
  
  <p>I don't need these changes (database creation) to be tracked by liquibase, seems like I want to use LB as quick bootstrap tool.</p>