The `@DEV` marker is not required anymore as per discussion with @Seldaek
Clarifying on `composer require`, `composer update` and `composer install` as per discussion with @Stof

Ref: https://twitter.com/Stof70/status/543064766580002816
Merge pull request #3 from Roave/hotfix/installation-notes-clarifications

Installation notes clarifications/feedback as per discussion on twitter/IRC