918759: Update Thumbslug to use systemd.

Additionally:
- Use the jpackage_script macro to build the wrapper script for us.
- Add attrocious SELinux policy version hack.
  See https://fedoraproject.org/wiki/SELinux_Policy_Modules_Packaging_Draft#Runtime_Dependencies
- Install thumbslug in the normal place for JARs.
- Build a proper jar repository. Don't just use everything in /usr/share/java.
- Add some SysVInit requires when not using systemd.
- Use %{buildroot} macro.  It's shorter.
Update thumbslug shell script to use jpackage-utils

This script is now very similar to what the %jpackage_script RPM
macro produces.
Put configuration files in their own directory.
Use more recent version of buildr.
Add resources to classpath for thumbslug script.
Accept a config file as an argument.

Necessary for testing when the default thumbslug conf file doesn't
exist on a system.
Fix thumbslug's spec tests.

The entitlement certificates that the tests used were expired, so
I generated new ones that will last until 2030 and placed all the
necessary information for the candlepin CA in the CA directory.

Additionally, the tests were not running correctly with the -jar
option, so we now just invoke the Main class directly and I altered
the way that flags were passed in to the JVM to make it a little
easier to add things in the future.
Use Candlepin checkstyle file to fix TreeWalker bug.

See http://sourceforge.net/p/checkstyle/bugs/682/
Add some documentation.
Systemd should accept Thumbslug's normal exit code.

When Thumbslug exits with a SIGTERM, it returns 143 (which is SIGTERM +
128; see http://tldp.org/LDP/abs/html/exitcodes.html) instead of 0.
Eventually we should fix Thumbslug to return 0 when it terminates
normally, but doing this is surprisingly hard.