Please unify structure for config files with impt

[thomaskoehn-kisi]

I'm creating this ticket here in the Sublime repo, as the employed structure in impt looks more modular to me and so the sublime plugin should rather follow the impt approach.

Please allow me to use the same configuration for github credentials and builder variables for both, the sublime plugin as well as impt test. Currently, this is not possible. Here is why:

Github Credentials

Sublime Plugin

• hard-wired stored in auth.info
• wrapped in builder-settings object
• uses github-token and github-user keys

Example

{
    "builder-settings": {
        "github-token": "lalallalalalalalallala", 
        "github-user": "thomaskoehn-kisi"
    }
}

impt test

• freely configurable with impt test update --github-config <file>
• not wrapped in builder-settings object
• uses githubUser and githubToken keys

Example

{
  "githubUser": "thomaskoehn-kisi",
  "githubToken": "lalallalalalalalallala"
}

Suggestion

• use structure of impt test version also for sublime plugin

Builder Variables

Sublime

• has them inside electric-imp.settings
• inside object variable-definitions

impt test

• has them in a dedicated file
• no extra root level object

Suggestion

• use dedicated file in the style of impt test also for sublime plugin
• allow to specify file path for this file in electric-imp.settings