Add ENV variables support for few configuration option

[nazarhussain]

Expected behavior

We should specify many configuration option through ENV variables. That is required to have a configureable docker image (template file, confd and invocation (in run.sh) must be removed from the docker image)

Actual behavior

Currently we support some subset of configuration options to be set through the ENV variables. https://github.com/LiskHQ/lisk/tree/1.1.0#command-line-options, which are not enough to run a docker image

Which version(s) does this affect? (Environment, OS, etc...)

1.1.x

[nazarhussain]

After discussion among @fchavant and @diego-G we decided to move this issue to 1.2.0 or later. As in 1.1.0 we had came across of an alternative solution to keep the template file for docker.

@fchavant will provide list of configuration options those are absolutely needed to run the docker image

@diego-G Need to provide the most common configuration options that our app will support from user perspective in addition to already supported 5 env variables. https://github.com/LiskHQ/lisk/tree/1.1.0#command-line-options

We will support short listed configuration options through env variables and for rest of the detailed configuration user have to use its own custom config file in docker.

[fchavant]

@nazarhussain at the very least we need to be able to set:
.consoleLogLevel, .db.host, .cacheEnabled, .db.user, .db.password and .api.access.public.

[nazarhussain]

@diego-G Can you please confirm that there is no need of other env variables?

[diego-G]

fileLogLevel, consoleLogLevel, cacheEnabled, db.host, db.user, db.password, api.access.public, forging.access.whitelist[], forging.delegates[], peers.list[]. The last three are arrays as you can appreciate. They might include several elements.