add support for transactions

[seancarr]

startTransaction() and commitTransaction() would be helpful functions at the database level

startTransaction could look something like:
dbConn.getConnection().setAutoCommit(false);
savepoint = dbConn.getConnection().setSavepoint();

and commitTransaction could look like:
dbConn.getConnection().commit();
dbConn.getConnection().setAutoCommit(true);

rollbackTransaction would be a little more involved