fix appFile to array on getAppDirs in lib/devices/ios/simulator.js

In ios8 branch, I found a bug that sometimes customApp directory, exist under ~/Library/Developer/CoreSimulator/Devices/xxxx/data/Applications/, remaining even cleanCustomApp called with ios7 caps.

In this pull request fix it.

After adopting this pull request, customApp directory in ~/Library/Developer/CoreSimulator/Devices/xxxx/data/Applications/ removed every cleanCustomApp called.