Should fail on JSON fields duplication

[vl021188]

There is an issue with comparion of JSON with duplicated fields:

    @Test
    public void testJSONAssert() throws JSONException {
        String expected = "{\"field\":\"val1\"}";
        String actual = "{\"field\":\"val2\",\"field\":\"val1\"}";
        JSONAssert.assertEquals(expected, actual, JSONCompareMode.STRICT);
    }

This test has passed but it don't looks like expected behavior.

The issue is actual for Jackson serializer in java. It behaves incorrect in some cases and I would like to check it in my tests.

[vl021188]

I suggest to use 'org.json:json:20180130' instead of 'com.vaadin.external.google:android-json:0.***'.

[vl021188]

Please look at the pull-request: #96