I had the same error and finally decided to try a different package of the same version and it started to work.
I downloaded:
liquibase-3.0.4-bin.zip
rather than:
liquibase-3.0.4-bin.tar.gz
liquibase.properties
#liquibase.properties
driver=com.mysql.jdbc.Driver
classpath=/root/scripts/liquibase/lib/mysql-connector-java-5.1.17.jar:/root/scripts/liquibase/lib/snakeyaml-1.12.jar
changeLogFile=changelog/blah-diff-changelog.xml
url=jdbc:mysql://localhost:4000/blah
username=temp
referenceUrl=jdbc:mysql://localhost/blah
referenceUsername=temp
logLevel=info
logFile=log/liquibase.log
The mysql connector in liquibase/lib is just a symlink.