added docs for new v2 features
restructures modules bar and core/extras info into their own pages
changed templates to refer to the new pages
added some missing ansible.cfg options
more info on gathering setting
Had to shoot the recently merged nova_group module in the head temporarily as it contained a dict comprehension, which means it can't work on all the platforms
and was also breaking docs builds on CentOS. Will engage with list about that shortly.
