Add methods for missing Harry Potter entries

src/main/java/com/github/javafaker/HarryPotter.java

@@ -22,4 +22,12 @@ public class HarryPotter {
     public String book() {
         return faker.resolve("harry_potter.books");
     }
+
+    public String house() {
+        return faker.resolve("harry_potter.houses");
+    }
+
+    public String spell() {
+        return faker.resolve("harry_potter.spells");
+    }
 }

src/test/java/com/github/javafaker/HarryPotterTest.java

@@ -28,4 +28,14 @@ public class HarryPotterTest extends AbstractFakerTest {
     public void book() {
         assertThat(faker.harryPotter().book(), matchesRegularExpression("Harry Potter and the ([A-Za-z'\\-]+ ?)+"));
     }
+
+    @Test
+    public void house() {
+        assertThat(faker.harryPotter().house(), matchesRegularExpression("[A-Za-z ]+"));
+    }
+
+    @Test
+    public void spell() {
+        assertThat(faker.harryPotter().spell(), matchesRegularExpression("[A-Za-z ]+"));
+    }
 }