Adjust cabal file to support building w/o assistant on the hurd.

I used to have this and hackage rejected the os(gnu), so I am going to see
if the new hackage still rejects it.
add note about wheey backport container
Merge branch 'master' of ssh://git-annex.branchable.com
add encryption setting to examples
Merge branch 'master' of ssh://git-annex.branchable.com