Add summary to bottom of test runner output.

Also, don't sort tests by #hosts when run sequentially, and fix typo in run_all.sh.

Fixes #1240

test/run_all.sh

@@ -19,7 +19,7 @@ if [ -n "$CIRCLECI" -a -z "$NO_SCHEDULER" ]; then
 fi
 
 # If running on circle or PARALLEL is not empty, run tests in parallel
-if [ -n "$CIRCLECI" -o -z "$PARALLEL" ]; then
+if [ -n "$CIRCLECI" -o -n "$PARALLEL" ]; then
     RUNNER_ARGS="$RUNNER_ARGS -parallel"
 fi