Small test fixes.

One test method was missing `@Test` so it was never run.

One test method used another test class as the base for finding a test
resource. While this works in practice with Maven, it is not strictly
right.

src/test/java/org/json/junit/JSONObjectTest.java

@@ -3288,6 +3288,7 @@ public class JSONObjectTest {
      * Sample test case from https://github.com/stleary/JSON-java/issues/531
      * which verifies that no regression in double/BigDecimal support is present.
      */
+    @Test
     public void testObjectToBigDecimal() {  
         double value = 1412078745.01074;  
         Reader reader = new StringReader("[{\"value\": " + value + "}]");