[NEW] Integrated GCM and added notifications support

Retrieve public settings on login screens

generated google-services.json file including chat.rocket.android.dev
app within clients

- in memory repository for settings for now (will move to DB)
- repository and interactors for Current server

Remove the SDK as an module

[NEW] Show list of chats using the SDK (pure online)

Develop-2.x

[LAYOUT] Finishing authentication screens

Add generic error, remove unneeded parammeters , add AuthenticationNavigator properties.

Merge branch 'feature/show-chat-list-using-sdk' of https://github.com/filipedelimabrito/Rocket.Chat.Android into filipedelimabrito-feature/show-chat-list-using-sdk