Renamed WEPIFRutimeException to WEPIFRuntimeException and gave it a serialVersionUID.

src/main/java/com/sk89q/wepif/WEPIFRuntimeException.java

@@ -0,0 +1,12 @@
+package com.sk89q.wepif;
+
+/**
+ * @author zml2008
+ */
+public class WEPIFRuntimeException extends RuntimeException {
+    private static final long serialVersionUID = 1L;
+
+    public WEPIFRuntimeException(String message) {
+        super(message);
+    }
+}