Add default config command

[hahmed]

Adding a default config command so we can use gel like so;

gel config

Which will output all the default config settings, e.g.

jobs=3
gem.test=minitest
gem.mit=true

[matthewd]

Oops... (while jobs isn't a valid config setting anyway,) this isn't supposed to look like that.

I think this:

gel/lib/gel/config.rb

Line 20 in 6edbbe0

group, key = key.split(".", 2)

needs to be followed by something like:

group, key = nil, group if key.nil?

On the other hand, maybe we should change the file format (or group/key format?) to something different. The current behaviour looks not-great when key is a DNS name, as #73's example shows for packages.shopify.io. But that's a thought for another day.

[hahmed]

With bundle config local.GEM_NAME /path/to/local/git/repository and bundle config jobs 5 we get the output:

.bundle % cat config
---
BUNDLE_GEM__TEST: "minitest"
BUNDLE_JOBS: "7"
BUNDLE_LOCAL__GEM_NAME: "/path/to/local/git/repository"

To be honest bundlers output is not great either - WDYT? I'm going to give this a little more thought.

[hahmed]

@matthewd I downcased to keep all settings consistent, also strip the value too. Without the null check & some tests fail, I think it's because somewhere we are using the default -- bundler version for the config where we run all our tests, is that how it's supposed to work?