Loading a schema file breaks when a table does not already exist

When trying to load a schema file into Oracle, I got this error when a table did not exist:

    NativeException: java.sql.SQLSyntaxErrorException: ORA-00942: table or view does not exist: DROP TABLE "ORGANIZATIONS"

This change fixed this for me. It is modeled on a similar fix made a couple years ago to the activerecord-jdbc-adapter project: https://github.com/jruby/activerecord-jdbc-adapter/issues/48