Use env var to load Clair conf

[RiceBowlJr]

Type: feature

In here, is it possible to use a flag to use env var to load Clair conf to be compliant to Docker usage?
Or try to load var env and if not present load the config file, I think this is the way it is done generaly.

Do not hesitate to get back to me if you need more infos, meanwhile I'll try to implement it myself with the few knowledge I have.