Removed /etc/cron.* from Makefile

Since we are checking for the existence of these files in the
cron-*.service units it is no longer necessary to ship these
directories.
Check if /etc/cron.* exists and is non-empty
Fixed: Don't install /etc
Added myself to the LICENSE file
Added trailing newline in service files
Merge pull request #2 from WithHat/conditionals

Conditional execute cron-*.service units