Create start-up interface

[tbalouet]

We need a start-up interface when an user access the URL. This interface will be as follow:

1. has a "video" intro to explain game concept ("send the viking to valhalla")
2. "Enter your nickname" field
3. shows up 2 buttons: "Create game" and "Join Game", asking the user to enter a room name to join or create (and then share with his(/her) friends)
4. a share button to share the room he(/she) is in
5. allows the main 3D scene to load, fetchs to server to be done
6. VR users are at this point in the VR mode, so we need VR interfaces for the rest and previously a button to launch VR
7. shows up how many users are connected to the room, which device (->game post) they have
8. the room creator will have a "launch game" button when he feels everybody is ready (meaning enough people are connected). In the meantime other users will have text info "Waiting for the creator to launch"
9. once launched, the room will become available users dive in it and game starts after a few seconds, allowing contemplation