Add `flutter_local_storage` and `dart_jsonwebtoken`

[nazrinharris]

There are a couple of things that needs to be done to make flutter_secure_storage work. Of which can be found at the pub, https://pub.dev/packages/flutter_secure_storage.

• [x] Config for android (minSdkVersion >= 18)
• [x] Config for macOS
• [x] Config for iOS

Since there's new package addition, of which interacts quite directly with the platform, pod version issues and the like popped up! (yay). But these commands:

flutter pub upgrade --major-versions 
cd ios && pod deintegrate
cd ios && rm -f Podfile.lock
flutter packages get
cd ios && pod install --repo-update

Essentially fixed everything. Though do note that this needs to be done in both ios and macos! (of course, if you're planning to deploy on macos which I am.)

[nazrinharris]

Oh there's also some minor here and there things (like setting the min ios version), but that's for future me's headache!

[nazrinharris]

Should be completed with ecceaae in #132