[WIP] #63 + add verbose filter to getAction() and getCollectionAction() of ClassContentController

This option is passed as query parameter; it's necessary to lighten get classcontent action response;

The reduction is done by unsetting classcontent entry provided by classcontent definition (like maxentry, minentry, accept and properties)

I did some benchmarks:

- get article collection (26 items) with verbose true: response with over 20k lines
- get article collection (26 items) with verbose false: response with ~9k lines

It still heavy so we have to discuss about this with @crouillon.