Simplified the parameters.yml file
feature #722 Simplified the parameters.yml file (javiereguiluz)

This PR was squashed before being merged into the 2.6-dev branch (closes #722).

Discussion
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Simplified the parameters.yml file

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | -
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Originally, the `parameters.yml` was designed to define the infrastructure-related settings (in other words, the settings that may change from one computer to another). Meanwhile, the `config_*.yml` files are the ones that define the application behavior (in other words, the settings that stay the same from one computer to another).

In my opinion, the three removed parameters are related to application behavior and they shouldn't be defined at the `parameters.yml` file.

Commits
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48d4ad9 Simplified the parameters.yml file