Fix ObjectId compareTo for Java 6

JAVA-1785

Author: rozza

bson/src/main/org/bson/types/ObjectId.java

@@ -409,7 +409,7 @@ public int compareTo(final ObjectId other) {
         byte[] otherByteArray = other.toByteArray();
         for (int i = 0; i < 12; i++) {
             if (byteArray[i] != otherByteArray[i]) {
-                return Integer.compare(byteArray[i] & 0xff, otherByteArray[i] & 0xff);
+                return ((byteArray[i] & 0xff) < (otherByteArray[i] & 0xff)) ? -1 : 1;
             }
         }
         return 0;