Added Zoom behavior and example to demo. Still some bugs
Added zoom but still some bugs
Added comments
Added ZoomEvent inner class and fixed Zoom Demo. Thanks Anthoni!
Added documentation and made Pan-Zoom demo
Added gitignore so d3demo folder would not keep tracking GWT generated files
Removed GWT generated files
Removed d3demo directory
Add more gitignore files to ignore auto generated folders
Merge branch 'zoom'

Conflicts:
	gwt-d3-api/src/main/java/com/github/gwtd3/api/D3.java
	gwt-d3-demo/src/main/java/com/github/gwtd3/demo/client/D3Demo.java