Are you sure you have the right library? The SparkFun page (https://www.sparkfun.com/products/9954) points to two different libraries. One is called "Experimental WiFly Arduino Library" so I tried the other one, called "WiFly Library (Arduino 1.0)": WiFly-Shield/src/WiFly at master · jmr13031/WiFly-Shield · GitHub
The one I tried downloaded fine (as a .zip file). I unpacked it and moved the "WiFly" directory to my libraries directory. I re-started Arduino and was able to compile the "WiFly_WebServer" example without error.
Where did you get your WiFly library?