Add in new relic monitoring capability

To start with, we're just going to enable this in preview.
By default development should be off.

Need to be conscious about switching it on as it does introduce some overhead and memory usage.
Ah yes, I forgot, our unique snowflake setup.

There is no preview and staging, it all *thinks* it is production.

>_<
Remove redundant group
Merge remote-tracking branch 'origin/add_new_relic'