Removed the `scripts` field on composer config

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Related tickets | 
| License       | MIT

The `scripts` field is useless on a library package.

From the composer documentation v1.0:

> Note: Only scripts defined in the root package's `composer.json` are
> executed. If a dependency of the root package specifies its own scripts,
> Composer does not execute those additional scripts.