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.
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.