This change fixed IMPALA-4873 by adding the capability to supply a dict
'test_file_vars' to run_test_case(). Keys in this dict will be replaced
with their values inside test queries before they are executed.
Change-Id: Ie3f3c29a42501cfb2751f7ad0af166eb88f63b70
Reviewed-on: http://gerrit.cloudera.org:8080/6817
Reviewed-by: Michael Brown <mikeb@cloudera.com>
Tested-by: Impala Public Jenkins