[config] `containers`

[tristan-f-r]

Config file options should be under a general containers rule, so we can not only specify it per config, but also per algorithm and per analysis. This should make it easier to develop algorithms locally without having to switch out the docker user for every single algorithm globally.

Essentially, moving:

container_framework: docker
unpack_singularity: false
container_registry:
  base_url: docker.io
  owner: reedcompbio

to:

containers:
  framework: docker
  unpack_singularity: false
  registry:
    base_url: docker.io
    owner: reedcompbio

[agitter]

To make it per algorithm and per analysis, is the suggestion that you could have this global containers block but then override it with the same block nested under an algorithm?