[SPARK-2849] bin/spark-submit should respect spark.driver.* for client mode

We currently respect these configs only for cluster mode. From the names of the configs themselves, however, there is every reason for the user to believe that these should also apply for client mode. This currently does not work only because we're missing the code for it, and this PR adds this missing code.
I'm not sure you want `/g` here, in the unlikely case that `$1` is part of the option's value.