Added basic channel subscription and feed pages (#620)

Added basic channel subscription and feed pages

- Room Persistence for sqlite support.
- RxJava2 for reactive async support.
- Stetho for database inspection support.
- Enabled Multidex for debug build.

app/src/debug/AndroidManifest.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest
+    package="org.schabi.newpipe"
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.WAKE_LOCK"/>
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
+
+    <application
+        tools:replace="android:name"
+        android:name=".DebugApp"/>
+
+</manifest>

app/src/debug/java/org/schabi/newpipe/DebugApp.java

@@ -0,0 +1,63 @@
+package org.schabi.newpipe;
+
+import android.content.Context;
+import android.support.multidex.MultiDex;
+
+import com.facebook.stetho.Stetho;
+
+/**
+ * Copyright (C) Hans-Christoph Steiner 2016 <hans@eds.org>
+ * App.java is part of NewPipe.
+ *
+ * NewPipe is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * NewPipe is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with NewPipe.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+public class DebugApp extends App {
+    private static final String TAG = DebugApp.class.toString();
+
+    @Override
+    protected void attachBaseContext(Context base) {
+        super.attachBaseContext(base);
+        MultiDex.install(this);
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+
+        initStetho();
+    }
+
+    private void initStetho() {
+        // Create an InitializerBuilder
+        Stetho.InitializerBuilder initializerBuilder =
+                Stetho.newInitializerBuilder(this);
+
+        // Enable Chrome DevTools
+        initializerBuilder.enableWebKitInspector(
+                Stetho.defaultInspectorModulesProvider(this)
+        );
+
+        // Enable command line interface
+        initializerBuilder.enableDumpapp(
+                Stetho.defaultDumperPluginsProvider(getApplicationContext())
+        );
+
+        // Use the InitializerBuilder to generate an Initializer
+        Stetho.Initializer initializer = initializerBuilder.build();
+
+        // Initialize Stetho with the Initializer
+        Stetho.initialize(initializer);
+    }
+}