Merge pull request #188 from eonarheim/dev-erik

Merge Yui Documentation into master
Merge pull request #197 from eonarheim/dev-erik

Merge event targets and pausing engine bug fix
Merge pull request #203 from eonarheim/dev-erik

Added circular spawns for particle emitters, update docs, fixed sound stop bug, SpriteFonts can have different colors now
Update CONTRIBUTING.md
Update README.md
Update README.md
Update concatenation order for plain artifact
Fix Travis icon path
Close #95 Simplified spriteFonts, Labels now have drawing responsibility
Merge branch 'master' of github.com:eonarheim/Excalibur into dev-erik