update service log type to include exception message

src/main/java/edu/umd/dawn/common/exceptions/CustomExceptionHandler.java

@@ -32,8 +32,11 @@ public class CustomExceptionHandler {
     private ResponseEntity<Object> returnDawnException(DawnException exception) {
         if (exception.getBase() != null) {
             MDC.put("stackTrace", getStackTrace(exception.getBase()));
+            MDC.put("exceptionMessage", exception.getBase().getMessage());
         } else {
             MDC.put("stackTrace", getStackTrace(exception));
+            MDC.put("exceptionMessage", exception.getMessage());
+            // MDC.put("exceptionMessage", exception.)
         }
         log.error(exception.getMessage());
         MDC.remove("stackTrace");