Start using asterisks instead of carets in composer.json?

[ostrolucky]

http://symfony.com/doc/current/setup.html says you can install specific symfony version via flex constraint. But this is not really true, because composer create-project symfony/skeleton test "3.3.*" won't install symfony 3.3.* packages, but >3.4 packages, because they are more recent. Now, I have also created PR in docs to stop mentioning this. It's on you which path this goes.

To be clear, I propose to require e.g. symfony/console 3.3.* in 3.3 branch, instead of ^3.3 and symfony/console 3.4.* in 3.4 branch, instead of ^3.4