added D3.rgb(color) and D3.hsl(color) methods taking an existing color
object
ghost commit
Merge branch 'colors-api'

Conflicts:
	gwt-d3-api/src/main/java/com/github/gwtd3/api/D3.java
	gwt-d3-api/src/main/java/com/github/gwtd3/api/core/Color.java
	gwt-d3-api/src/main/java/com/github/gwtd3/api/core/RGBColor.java
	gwt-d3-demo/eclipse-launch-profiles/UpdateApplication.launch
	gwt-d3-demo/src/main/java/com/github/gwtd3/demo/client/testcases/d3/TestColors.java
	gwt-d3-demo/src/test/java/com/github/gwtd3/demo/client/pageobjects/NavigationButton.java