Added accessor functions to Zoom
Merge branch 'master' of https://github.com/gwtd3/gwt-d3

Conflicts:
	gwt-d3-api/src/main/java/com/github/gwtd3/api/behaviour/Zoom.java
Updated Zoom to previous commit with accessor functions
Merge pull request #64 from augbog/master

Added Accessor Functions to Zoom