Add caffe and gcc

The script now fails if caffe is in compatible. I also added gcc because compiling with gcc from the host PC (Idiap machines) .

Let's put this idea of certification on bob.nightlies to use with this change. I'm afraid installing gcc will cause repercussions.

So, in other words, let's not run "from-scratch.sh" on the CI machines just yet.

mentioned in commit 5b7ad326

merged

mentioned in commit 4edf32eb

mentioned in merge request !28 (merged)

mentioned in commit f080f858

mentioned in commit 03767a33

mentioned in merge request !29 (merged)

mentioned in commit b8035a05

mentioned in commit cd10a3b1

mentioned in merge request !33 (closed)