Fixing composer branch alias.

Currently the master and develop branches both try to alias dev-develop to 1.3-dev and 2.0-dev. This is not possible, nor makes any sense.

This leads to 2.0.*@dev existing on packagist, but not 1.3.*@dev and ends up causing people to use dev-master which is bad.

This fixes that, allowing users to now require 1.3.*@dev