Replace sprites

Also fixed gitignore (for windows?) to ignore JS files
Add left and right jumping, don't play left/right animations when in air
Add todos
Mod speed and fix flipped run animation
Close #49 - Implement a .kill() method as a shorthand to remove actors from the scene graph
Close #54 Implement SceneStack
Fix #84 simplified loading, added an optional done callback to the game.load method
Close #86 implement promises in Excalibur, added a Promise.wrap to wrap non promise values in a resolved promise
Added generic types to promises :)
Added promises to loaders
Added Excalibur loading image to default loader
Merge remote-tracking branch 'origin/master' into 35-replace-assets
Merge pull request #88 from eonarheim/35-replace-assets

[#35] Replace assets
Close #78 IDrawable's can now be flipped on x and y
Resolve ambiguity on #78 flipX will flip on the X axis and flipY will flip on the Y axis, added clamp function to util
Close #89 clearActions now implemented
Close #85 add different display modes for the engine including the proposed container mode, fixed appending canvas bug
Merge pull request #90 from eonarheim/dev-erik

Merge code complete for v0.1 :)
Update logo dark image
Update README.md