Fix link in CONTRIBUTORS.md
Fix link in CONTRIBUTORS.md

The last person to add their name to the file had a space between the
link text and URL. Removing the space should get the link to display properly.

jasonbeverage/cesium,YonatanKra/cesium,likangning93/cesium,likangning93/cesium,YonatanKra/cesium,jasonbeverage/cesium,progsung/cesium,AnalyticalGraphicsInc/cesium,progsung/cesium,YonatanKra/cesium,likangning93/cesium,CesiumGS/cesium,AnalyticalGraphicsInc/cesium,YonatanKra/cesium,CesiumGS/cesium,likangning93/cesium,CesiumGS/cesium,CesiumGS/cesium,likangning93/cesium,CesiumGS/cesium