boost: Add optional Boost.MPI support

Boost.MPI is a C++ interface library to the
message passing interface (MPI) standard.
ConTeXt: Update to a current version & include it in texLiveFull.
vim-configurable: update the patch-version
gtk3 stack: go back to gnome-3.12 branches for now
Allow starting a shell on stage 1 failure

When people copy the ISO to USB it can happen that the root device isn't known. Having a shell greatly improves that situation.
libfm: update frm 1.2.2.1 to 1.2.3
pcmanfm: update from 1.2.2 to 1.2.3
sxiv: update revision

Mainly to kick off Hydra again: it thinks the build is broken because we
used a SSH URL for git before.
mpd: update to 0.19.3
goffice_0_8: Fix build
kyotocabinet: Add derivation
tokyocabinet: 1.4.46 -> 1.4.48
leveldb: 1.15 -> 1.18
ceph: 0.87 -> 0.88
pcsclite: 1.8.12 -> 1.8.13
dhcp: 4.3.0 -> 4.3.1
btrfs-progs: 3.17 -> 3.17.1
kernel: 3.17.2 -> 3.17.3
kernel: 3.14.23 -> 3.14.24
libnl: 3.2.23 -> 3.2.25