Add loading screen

[azeier]

Based on #81.

• "Waiting for X..." messages are now logged, rather than displayed.
• I added a few random loading messages that came to mind. They are randomly picked from.
• There is probably a better way to do the html/css.
• Currently doesn't scale with app size - probably doesn't matter.
• Not amazing, but probably good enough for now. (at least better than "waiting for gamestate..." :))
  • Adding hero images might be nice - would require some preloading prioritization though.

https://cloud.githubusercontent.com/assets/7737910/14500565/eb5a9cbe-01a2-11e6-91e1-4fbd2c6bf5eb.gif

other way around:

[beheh]

I really like the second version, nice and smooth transitions as well. Feedback from others? I can look into the scaling. We should also outsource the loading screen into a new component.

[jleclanche]

I prefer the clockwise one as well.

[azeier]

• Updated to spin clockwise.
• Moved loading screen to it's own component

[beheh]

Replaced by #118, some of the code will be reused.