Add Movlw instruction (#7)

commands/Movlw.java

@@ -0,0 +1,19 @@
+package commands;
+
+import registers.Memory;
+
+public class Movlw extends CommandUtils implements Command
+{
+    private final int literal;
+
+    public Movlw(int input)
+    {
+        literal = input & 0x00FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        Memory.workingRegister = literal;
+    }
+}