LCG_94 Update, master branch (2018.09.17.)

As discussed in !330 (closed), that MR was never meant to be merged in. It was just to run tests with LCG_94rc1. This is the update that we should merge into master...

I simply just cherry-picked 4 out of the 5 commits of !330 (closed), and added one that upgrades all projects from LCG_93c to LCG_94.

I'm still running some tests with the branch myself, but wanted to open the MR already now nevertheless. So that once/if local tests succeed, I'd be able to merge and tag this update already today.

Just mentioning everyone explicitly that was also on !330 (closed). @ssnyder, @mnowak, @dguest, @obreshko, @rhauser, @wlampl, @ivivarel, @emoyse.