Replace lumberjack with logstash-forwarder

- Upgrading in the hope we will stop logstash running out of memory and
   crashing. If not at least we are running a later version of the software.
   This PR https://github.com/elasticsearch/logstash-forwarder/issues/212 seems
   to suggest there may be issues with logstash forwarder. These logstash Jira
   tickets are also relvant - https://logstash.jira.com/browse/LOGSTASH-1253
   https://logstash.jira.com/browse/LOGSTASH-2168
 - Switch to the official elasticsearch logstash forwarder repo. There were a
   couple of issues with this which we would like to fix upstream -
 - For now add a symlink to correct the location the init script looks for the
   config file, as this is wrong in either the logstash-forwarder deb package or
   the puppet module
   https://github.com/elasticsearch/puppet-logstashforwarder/pull/12
 - There is an issue with file ordering in the puppet module. This means
   sometimes deploying using this module will fail
   https://github.com/elasticsearch/puppet-logstashforwarder/pull/13
 - The changes to our actual puppet code were renaming config params, using a
   different class, and renaming the defines to match the new puppet modules.

Add in code to remove lumberjack

This is a hack involving using the lumberjack module init and logshipper
manifests as skeleton from which we hang a lot of ensure absents. This will
be removed in a further clean up pr.

In order for this to be deployed you must first run:

```
fab <ENVIRONMENT> all sdo:'mkdir -p /etc/logstashforwarder/'
```

And after you must run

```
fab <ENVIRONMENT> all sdo:'killall lumberjack'
```