This is a very old thread, but in googling for this it's one of the few hits that came up - so in case anyone else ever trips over the 'with driver java.lang.String' problem, here's a quick fix.
In my case, the URL in the properties file was surrounded with quotes (which is sometimes needed on the command line). Removing the quotes allowed liquibase to run fine. I believe the 'java.lang.string' error points to a problem in the JDBC URL - either bad formatting or unparseable content.
I hope this helps others...