Add Xml property to ArrayModel class

[rbsilva]

Q	A
Bug or feature request?	feature
Which Swagger-Core version?	1.5.19
Which Java version?	Java 8
Which JAX-RS framework & version?	-

Actual behaviour:

When creating a ArrayModel:

new ArrayModel().items(....);

The output json is:

{
   "type":"array",
   "items":{"$ref":"#/definitions/Payment"}
}

Expected behaviour:

When creating a ArrayModel with Xml:

new ArrayModel().items(....).xml(new Xml().wrapped(true).name("payments"));

The output json is:

{
   "type":"array",
   "items":{"$ref":"#/definitions/Payment"},
   "xml":{"name":"payments","wrapped":true}
}

[frantuma]

implemented in #2684

[rbsilva]

Thanks :)