Fixes typo in assert

Author: John J. Aylward

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

@@ -520,7 +520,7 @@ public void jsonObjectValues() {
     @Test
     public void stringToValueNumbersTest() {
         assertTrue("-0 Should be a Double!",JSONObject.stringToValue("-0")  instanceof Double);
-        assertTrue("-0 Should be a Double!",JSONObject.stringToValue("-0.0") instanceof Double);
+        assertTrue("-0.0 Should be a Double!",JSONObject.stringToValue("-0.0") instanceof Double);
         assertTrue("'-' Should be a String!",JSONObject.stringToValue("-") instanceof String);
         assertTrue( "0.2 should be a Double!",
                 JSONObject.stringToValue( "0.2" ) instanceof Double );