Android: redesigned navigation model

- redesigned layout, different conversations are now separate - like the SMS app
Android: further work on new model

- Got the basic things working, all conversations are now separate
Android: separate conversations probably finished

- Separate conversations fully implemented and working, will be merged after testing
- Help contents updated to match new model
- Application name changed to CryptoChat
Android: updated sponsor logo
Android: new model finished

- Separate conversations finished
- Prettier text on conversation list
- Removed unnecesary layout elements on conversation page
Merge pull request #1 from nidzo732/separateConversations

Separate conversations