Only require necessary info in runcards
Created by: voisey
One step towards closing https://github.com/NNPDF/nnpdf/issues/536.
So far this just removes the requirement for closuretest
and fakedata
to be specified in a runcard when running vp-setupfit. I can imagine there being a reason for what I've done being suboptimal, but I thought I'd just open it to the floor anyway so that you can just tell me