Upstream has not been tagging new versions for a long time, but we need
compatibility with newer kernels. The 0.6.2 versions already have a bunch of
backported compatibility patches, but 3.14 kernels need even more.
Also, the git versions have fixed a bunch of crashes and other bugs, so perhaps
we should just bite the bullet and just use recent git versions (as sometimes
upstream recommends, when people run into bugs).
This adds a new "boot.zfs.useGit" boolean option, so that a user can
easily opt into using the git versions.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
(systemd service descriptions that is, not service descriptions in "man
configuration.nix".)
Capitalizing each word in the description seems to be the accepted
standard.
Also shorten these descriptions:
* "Munin node, the agent process" => "Munin Node"
* "Planet Venus, an awesome ‘river of news’ feed reader" => "Planet Venus Feed Reader"
