Fixing a ci-issue with factory-girls in development.

The rake db:migrate, that is used on jenkins, uses the
development-environment: The latest change to add sample-data for the
development-environment added a :group => :development to the
factorygirls-gem, which in turn loads the factories, which crashes in
planning_element_type_color.rb, when the ms_project_colors are loaded.

The short-term fix for this:

* removed the factory_girls-gem from :development
* removed the dependency from seeds/deveopment