Allow enabling coredumps.

Disabled by default, but allow admin to enable for debugging purposes.
Core dumps are stored as /tmp/cores/core.%e.%p.%h.%t.
Fix creating /etc/profile.d/editor.sh

The not_if test is broken: we don't need the echo (which will exit with
0), but we need the exit value of grep.
fix AutoYaST bootdevice fallback

Drop device section if the device is not set.
AutoYaST will decide on its own which device to use in that case.
Merge pull request #165 from jdsn/release/pebbles/master

fix AutoYaST bootdevice fallback
Merge pull request #162 from vuntz/fix-editor

https://github.com/crowbar/barclamp-provisioner/pull/162

Merged by devtool for cloudsleuth
Merge pull request #161 from saschpe/release/pebbles/master-coredump

Allow enabling coredumps.