Delete appBundleId.plist for iOS8

Under iOS7 Simulator, they stored appBundleId.plist in "Data/Application/xxxxxxxxxx/Library/Preferences/appBundleId.plist".
But iOS8 Simulator stored appBundleId.plist in "Library/Preferences/appBundleId.plist" directory.

So, I add deleting plist for parseFloat(this.platformVer) >= 8.

The following log is an example when I add this PR.
```
info: [debug] Cleaning sim preferences
info: [debug] Cleaning app data files
info: [debug] Deleting /Users/myname/Library/Developer/CoreSimulator/Devices/EEC7B8C2-AAAC-4456-A7D4-9CF679C94EB0/data/Containers/Data/Application/9583BD90-872C-44C0-A6E6-8CA3878F89DC
info: [debug] Deleting /Users/myname/Library/Developer/CoreSimulator/Devices/EEC7B8C2-AAAC-4456-A7D4-9CF679C94EB0/data/Library/Preferences/appBundleId.plist
info: [debug] Setting locale information
info: [debug] New language: ja
```

I add in cleanCustomApp because I referred PR https://github.com/appium/appium/pull/3756 .