More stable and robust

Added

• SDK now restarts tracking if it was tracking before the app restart
• Ignores all repeated commands (startTracking, stopTracking, name, metadata etc.) if new state is the same as the old one
• SDK sends silent push notification acknowledgments to backend. This results in more stable Trips experience
• Added error messages when static SDK methods are used before publishable key was set
• Increased robustness across all usage scenarios and states