[Development] CI configuration changes

[Morten Johan Sørvig]

> On 03 Dec 2014, at 18:33, Thiago Macieira <thiago.macieira at intel.com> wrote:
> 
> I will not be sorry to see it go, but if it goes I promise you we'll break 
> 10.7 support within one week (the forkfd work failed on 10.7 for unknown 
> reasons and I will submit it with clear conscience as soon as the 10.7 it out 
> of CI).

Would it make sense to use this on newer OS X versions only and keep the current code paths for legacy OS support? We currently do this in cases where we want to use new API.

Morten