Ensure log directory exists before starting service

If it doesn't, logstash will (silently!) fail to start.
Provide complete containment

Prevent the package class from floating off, causing package
installation to be attampted before repositories are defined.
Ensure LS_JAVA_OPTS are appended to, not overwritten

We probably don't want the user to accidentally overwrite the temp dir.
Fix typo in $logstash_user
Put anchors together for consistency with elasticsearch module
Resolve puppet-lint whitespace errors
Merge pull request #53 from blalor/master

Fix containment, create log dir, preserve java.io.tmpdir