Feature Request: add unix socket config for Redis cache

[DeeKey]

Currently it is not possible to configure nginx-helper to run Redis via unix sockets which is faster method.
Would be nice to have an ability to have it.

[gridpane]

Forked and working on this

[gridpane]

I have a working version here:

https://github.com/gridpane/nginx-helper

Can set the redis socket via admin

Or via constants

Also covered configuring database, and ACLs... will create another issue for this...

Am completing testing for our platform and will create a PR back to master....

[gridpane]

#344