Merge pull request #262 from offlinehacker/fix/stage_2_lib_var_db

stage-2-init: create /var/lib and /var/db at boot, so some modules that create user home folders here don't fail
Added support for -I flag to nixos-install
Don't spam the user
Don't disable D-Bus if environment.noXlibs is set

D-Bus cannot be disabled since systemd/logind depend on it.
The testing interface does not take nixpkgs as a parameter anymore => fix this
Fix run-in-machine testcase + add it to the tests
Unify the two Memtest modules

This means we now have Memtest86+ on the installation CD.
Move run-in-machine test to a different place, because it does not conform to the other testcases' interface
Use "cp" instead of "rsync" for VirtualBox image generation

Rsync appears to use a lot of memory.  Fixes #266.
zope2 service (plone)
Prettify graphite service

cc @offlinehacker
zope2 service fixes
some more zope2 service improvements
adding http_address option to varnish service
Make glib_networking available for dwbem
firebird service
many suggestions contributed by bjornfor and edolstra
Merge pull request #209 from MarcWeber/submit/firebird

systemd/firebird
Remove the nixos.unstable job from the trunk-combined jobset
Properly wipe .compose-cache.
Fixes #267.
add simple rsnapshot module