Add gallery spider

app/src/main/java/com/hippo/ehviewer/gallery/GalleryLoaderImpl.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2015 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.ehviewer.gallery;
+
+public interface GalleryLoaderImpl {
+
+    void request(int index);
+
+    int size();
+}