If you are like me and you run an older version of OS X, Mavericks in my case, it means that you may run into the problem with PhpStorm that you can’t use composer. It seems like you are stuck in this rut. Well, I’m going to put this here mainly for my own memory, and in the hopes that it brings someone else luck in getting PhpStorm working correctly.
https://youtrack.jetbrains.com/issue/WI-27354#comment=27-999854