Upgrade the dependencies of the "RealmTasks React" app

[kraenhansen]

A lot of stuff has happened in the React / React Native projects that we should adapt our example app to. After updating react-native remember to run react-native upgrade or consider starting an entirely new React Native project.

In its current state I'm unable to build "RealmTasks React" for iOS with xcode 9:

** BUILD FAILED **

The following build commands failed:
CompileC /Users/kraenhansen/Repositories/realm-tasks/RealmTasks\ React/ios/build/Build/Intermediates.noindex/React.build/Debug-iphonesimulator/React.build/Objects-normal/x86_64/RCTJavaScriptLoader.o Base/RCTJavaScriptLoader.mm normal x86_64 objective-c++ com.apple.compilers.llvm.clang.1_0.compiler
(1 failure)

Installing build/Build/Products/Debug-iphonesimulator/ReactExample.app
An error was encountered processing the command (domain=NSPOSIXErrorDomain, code=2):
Failed to install the requested application
An application bundle was not found at the provided path.
Provide a valid path to the desired application bundle.
Print: Entry, ":CFBundleIdentifier", Does Not Exist

Command failed: /usr/libexec/PlistBuddy -c Print:CFBundleIdentifier build/Build/Products/Debug-iphonesimulator/ReactExample.app/Info.plist
Print: Entry, ":CFBundleIdentifier", Does Not Exist