checker: Update checker to use grade.sh

Update checker to use `grade.sh` script to print out results.

Signed-off-by: Razvan Deaconescu <razvan.deaconescu@upb.ro>

checker/checker.sh

@@ -5,13 +5,8 @@
 rm -fr ../tests/
 cp -r "$CHECKER_DATA_DIRECTORY"/../tests ..
 
-# Everything happens in the tests/ directory.
+# Checking and grading happens in the tests/ directory.
 pushd ../tests > /dev/null || exit 1
-
-echo -e "\n\n### RUNING CHECKER\n\n"
-make check
-
-echo -e "\n\n### RUNING LINTER\n\n"
-make lint
-
+# Placeholder causes the printing of final results before the checker / linter details.
+./grade.sh placeholder
 popd > /dev/null || exit 1