test case for issue 225

I didn't want to mess around with forked submodules, so here's the proposed fix for com.couchbase.lite.View in couchbase-lite-java-core:

```java
    /**
     * Are key1 and key2 grouped together at this groupLevel?
     * @exclude
     */
    @InterfaceAudience.Private
    public static boolean groupTogether(Object key1, Object key2, int groupLevel) {
        if(groupLevel == 0 || !(key1 instanceof List) || !(key2 instanceof List)) {
            return key1.equals(key2);
        }
        @SuppressWarnings("unchecked")
        List<Object> key1List = (List<Object>)key1;
        @SuppressWarnings("unchecked")
        List<Object> key2List = (List<Object>)key2;
        
        // if either key list is smaller than groupLevel and the key lists are different
        // sizes, they cannot be equal.
        if ((key1List.size() < groupLevel || key2List.size() < groupLevel) && key1List.size() != key2List.size()) {
            return false;
        }
        
        int end = Math.min(groupLevel, Math.min(key1List.size(), key2List.size()));
        for(int i = 0; i < end; ++i) {
            if(!key1List.get(i).equals(key2List.get(i))) {
                return false;
            }
        }
        return true;
    }
```

The test in this PR fails when the size comparison is left out and succeeds when it is present.  All other view unit tests succeed.  Let me know if you have any questions or concerns about this change.