Managed to get a little further by putting file /usr/share/java/mysql-connector-java.jar in /usr/lib/ambari-server/web/resources
Then re-starting oozie caused the file to be transferred to proper directory /usr/hdp/current/oozie-server/libext
but now stucked with this message:
resource_management.core.exceptions.Fail: Execution of ‘/usr/jdk64/jdk1.8.0_40/bin/java -cp /usr/lib/ambari-agent/DBConnectionVerification.jar:/usr/hdp/current/oozie-server/libext/mysql-connector-java.jar org.apache.ambari.server.DBConnectionVerification ‘jdbc:mysql://myooziemachine/oozie’ oozie [PROTECTED] com.mysql.jdbc.Driver’ returned 1. ERROR: Unable to connect to the DB. Please check DB connection properties.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure