Add in var to point to current storage location for docker support files

Because of this post:

 

As you know, we have created a few predefined shares: system, appdata, domains, isos.

 

At present the only subdirs under system are:

./docker

./libvirt

 

Longer term we want to move the docker-related files currently downloaded to the flash (config/plugins/dockerMan) to the system/docker directory.

 

We can also create other subdirs there for maintenance purposes; maybe system/tmp could be used for your purposes?

I would like LT to take a pro-active approach and include the current storage location for the docker support files (currently /boot/config/plugins/dockerMan) as a variable within var.ini / docker.cfg, or accessible via the dockerClient class prior to implementation of moving the support files to the system folder (even if its hardcoded for the next couple of OS versions to /boot/config/plugins/dockerMan)

 

This would minimize the changes required to those plugins required to remain compatible with those future versions of unRaid.