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
Implemented chown file permissions and user/group creation
Ticket #62: File Permissions - user isn't set?
Verify mapped files exist in settings for all configs.
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
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
Fixed: user defined scripts in debian overridden by generated files
minor style fix
Merge pull request #93 from kardapoltsev/wip/etc-default

generating etc default, different postinst script for sysvinit
adds option to disable the java_version_check on linux
Merge pull request #97 from kardapoltsev/wip/user-defined-scripts

Fixed: user defined scripts in debian overridden by generated files
Merge pull request #100 from wallnuss/master

adds option to disable the java_version_check on linux
Fixed commands that were changed from camel case to dash-separated in the usage, fixed typo in Red Hat
Merge pull request #101 from jfim/patch-1

Fixed documentation for commands that were changed from camel case to dash-separated
Setting chdir to application directory. So logs get placed in the right
place (in play applications). Not relative to the /bin folder.
Adding /var/log/<application> directory and symlink to logging location