Add JSONP support to MappingJackson2JsonView

Enable JSONP support by wrapping the JSON output into
a callback parameter using the specified function name.

It could be enabled globally at MappingJackson2JsonView level,
or on a per request basis by adding an entry in the model using
MappingJackson2JsonView.JSONP_ENTRY_KEY as key and
the JSONP function name as value.

This commit also fixes JSONView support by removing the view
name specified in the model from the output.

Issue: SPR-8346