[Objective-C] Remove CocoaPods ignores

These should not be ignored by default, it's down to the user and they shouldn't forced to ignore the `Pods/` directory by default.

[http://guides.cocoapods.org/using/using-cocoapods.html#should-i-ignore-the-pods-directory-in-source-control?](http://guides.cocoapods.org/using/using-cocoapods.html#should-i-ignore-the-pods-directory-in-source-control?)