Plugin should not generate List-properties if maxOccurs defaults to 1

For the simplify-plugin, all examples in the reference have `choice`-elements with `maxOccurs="unbounded"`, which correctly results in List-properties. But if `maxOccurs` is not specified it defaults to 1, so there should not be List-properties but singular fields.

Example:

```xml

```

should rather result in

```java
@XmlElement(name = "foo", type = String.class)
protected String foo; // no List!
@XmlElement(name = "bar", type = Integer.class)
protected Integer bar; // no List!
```

for usage of ``