Error out with a useful message if a mapped file in unversal doesn't exist.

From https://github.com/sbt/sbt-native-packager/issues/23
Sysvinit script added
Some config options added to sysvinit template. Small code refactor
Start script system added to settings in Debian
Verify mapped files exist in settings for all configs.
sbt downgraded to 0.12.4, test for sysvinit-deb fixed
error creating symlink when file exists fixed
Merge pull request #86 from kardapoltsev/symlink-fix

error creating symlink when file already exists fixed
Merge pull request #85 from kardapoltsev/master

Sysvinit script for debian package
Merge pull request #84 from muuki88/master

Implemented chown file permissions and user/group creation
Merge pull request #83 from gmjabs/master

Informative failure for missing files mapped in universal
restart option added to sysvinit script, bug with wrong name for sysvinit script fixed
small bug fix
sysvinit template updated
sh changed to bash
Merge pull request #89 from kardapoltsev/master

Restart option added to sysvinit script
generating etc default, different postinst script for sysvinit
etc default added to conffiles
Do not declare java_cmd read-only as process_args will override it when -java-home is used
Merge pull request #95 from hackmann/master

Do not declare java_cmd read-only as process_args will override it