[Android] Preload chats and show them instantly

One deal-breaker for Rocket.Chat is definitely the 2 second wait time for loading a chat. All popular messaging apps like Whatsapp, Messenger, etc. quickly show the chat upon clicking. I think Rocket.Chat should do this too. Moreover, the “connecting” and “connected” thing at the top looks like app is in debugging mode. The app should stay connected in the background too and retrieve and store messages locally (I guess it does this but still it rearranges and loads from the local repository after opening the app).
I have made the above observations while using the app on my OnePlus 3 and open.rocket.chat server with both 4g and WiFi.

Have a pull request in widechat to fix this issue. https://github.com/WideChat/Rocket.Chat.Android/pull/332