Bump doctrine/orm to dev-master

The Sensio "clearCache" script, which is fired after composer install/update, is throwing an
exception as a file was removed from the "doctrine/orm" package. I've tried bumping up the
version from the minimum version constraint up to the latest tagged version but they either
produce errors or involve dependency conflicts which might prove tricky to resolve. A fix does
sit on master so temporarily moving to that.
Add composer.lock
Add check for development environment to the app_dev front controller
Delete upgrade markdown files
README.md amend

Replace with a list that details deletions/modifications from upstream.
Bring in FOSUserBundle