rPackages: prefixing package-system-dependencies with 'pkgs.'

Closes #4217
xulrunner: stick to firefox's src attribute
VM builds: Use default kernel

(this was set to 3.10 when 3.4 was our default)
See commit d846e976564350b247600b87cd065b3e42440846.
neoload: provide fake fontconfig file (fixes chroot builds)
firefox: Update to 32.0.2.
thunderbird: update from 31.1.0 to 31.1.1
nixUnstable: Update to 1.8pre3823_53b044c
k3d: 0.8.0.2 -> 0.8.03
e2fsprogs: Update to 1.42.12
less: Update to 468
wdiff: Update to 1.2.2
sysstat: Update to 11.0.1 and install systemd units
Bring back Boost 1.55 for now
mercurial: Update to 3.1.1
iproute2: Update to 3.16.0
Added luaPackages, moved lua sockets and lua filesystem to luaPackages, fixed mudlet deps
Simplified lua-packages function arguments to look nicer in all-packages
Switched from import to callPackage
Refactored to use callPackage right
Added description to languages-support.xml