iOS: clean up Todo app (remove dependencies from CocoaPods)

The TODO app source repo contains some code from the CocoaPods tool:
https://github.com/aerogear/aerogear-todo-ios/tree/master/AeroGear-TODO

• AeroGear-TODO.xcworkspace folder
• Pods folder
• Podfile.lock file

This should be removed (like in the aerogear-ios-integration project). the gitignore should also be updated and the README to indicate that pod install need to be executed before able to open the application.