Added a generic injector for commands

src/main/java/com/sk89q/minecraft/util/commands/SimpleInjector.java

@@ -0,0 +1,23 @@
+package com.sk89q.minecraft.util.commands;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+public class SimpleInjector<T> implements Injector {
+    private final T injectionObject;
+    public SimpleInjector(T injectionObject) {
+        this.injectionObject = injectionObject;
+    }
+
+    public Object getInstance(Class<?> cls) throws InvocationTargetException,
+            IllegalAccessException, InstantiationException {
+        try {
+            Constructor<?> construct = cls.getConstructor(injectionObject.getClass());
+            return construct.newInstance(injectionObject);
+        } catch (NoSuchMethodException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+}