Documented the sorter totals in the allocator.
Documented the sorter totals in the allocator.

This also updates a comment about the second stage of allocation
to reflect that the second stage is intended to allocate to roles
without quota.

Review: https://reviews.apache.org/r/64470/

jpeach/mesos,jpeach/mesos,andschwa/mesos,asamerh4/mesos,andschwa/mesos,gsantovena/mesos,abudnik/mesos,jpeach/mesos,jpeach/mesos,kaysoky/mesos,asamerh4/mesos,jpeach/mesos,dforsyth/mesos,reneploetz/mesos,dforsyth/mesos,gsantovena/mesos,dforsyth/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,asamerh4/mesos,dforsyth/mesos,asamerh4/mesos,asamerh4/mesos,kaysoky/mesos,chhsia0/mesos,dforsyth/mesos,dforsyth/mesos,asamerh4/mesos,chhsia0/mesos,andschwa/mesos,andschwa/mesos,gsantovena/mesos,Gilbert88/mesos,gsantovena/mesos,Gilbert88/mesos,reneploetz/mesos,reneploetz/mesos,jpeach/mesos,kaysoky/mesos,Gilbert88/mesos,Gilbert88/mesos,kaysoky/mesos,andschwa/mesos,abudnik/mesos,chhsia0/mesos,chhsia0/mesos,gsantovena/mesos,jpeach/mesos,abudnik/mesos,andschwa/mesos,Gilbert88/mesos,abudnik/mesos,reneploetz/mesos,gsantovena/mesos,abudnik/mesos,reneploetz/mesos,Gilbert88/mesos,kaysoky/mesos,asamerh4/mesos,andschwa/mesos,chhsia0/mesos,dforsyth/mesos,abudnik/mesos,Gilbert88/mesos,kaysoky/mesos,chhsia0/mesos,abudnik/mesos,reneploetz/mesos,kaysoky/mesos