Better difference description when using ElementSelectors.byNameAndAttributes #93

It'd be useful if difference description for a node that used node matcher with specific attributes, like this:
.withNodeMatcher(new DefaultNodeMatcher(
ElementSelectors.conditionalBuilder()
.whenElementIsNamed("SomeElem").thenUse(ElementSelectors.byNameAndAttributes("Attr1", "Attr2"))
.elseUse(ElementSelectors.byName).build()

would also have those attributes' values, like this:
Expected child 'SomeElem' but was 'null' - comparing <SomeElem Attr1="theValue1" Attr2="theValue2"...> at /RootElem[1]/SomeElem[16] to (DIFFERENT)