Get the environment from config.yml if available

[marcelovani]

I am having a little problem when running commands on a dev environment.
I followed the instruction in https://hechoendrupal.gitbooks.io/drupal-console/content/en/commands/settings-set.html and run
drupal settings:set environment dev

When I view the contents of ~/.console/config.yml I see:

    environment: dev

When I run drupal settings:debug
I get

 Config file : /Users/marcelovani/.console/config.yml

 Config key                                          Config value
 language                                            en
 environment                                         dev

So far, so good, but when I am on a dev environment, I would like all the commands to assume the --env option as dev, as per config. Likewise, if I am on stage, the default option should be that.

I have made a little change, to pull the settings from from config.
That should change the default option to whatever environment we are.
We still can override the environment by passing the --env option.
If there is no config, it will assume prod as it was before this PR.

I hope what I am suggesting makes sense.

[jmolivas]

@marcelovani Thanks for your contribution, your PR was merged. This will be included in the next release.