[Dependencies] - data-fixtures not found by composer

Some times happens that composer is not able to find doctrine/data-fixtures. After investigating a bit looks like composer does not recognizes the "*" for the version when searching for doctrine/data-fixtures and if you already have them installed composer says nothing. 
Many people are solving the problem by adding the dependence by hand with:
"doctrine/data-fixtures": "dev-master" in their composer.json.

This PR aims to solve that by changing it in the composer.json of the bundle.