Support for Jackson field-renames-getter heuristic

[julesfern]

Jackson supports the following behaviour:

public class Foo {
    @JsonProperty("renamed") private String foo;
    public String getFoo() { return foo; }    
}

When rendering JSON with Jackson, the getFoo method will correctly be interpreted as belonging to the marshalled "renamed" property.

Although support for @JsonProperty and @JsonIgnore were added in #321, the model parser was not respecting renames found at the field level after inspecting a corresponding public getter method. This patch is a fix.

Apologies if any of the code is horribly naive - totally open to receiving feedback and making this PR better.

[fehguy]

Hi, this was merged in #486