Integrate a Barcode Scanner

src/main/AndroidManifest.xml

@@ -7,6 +7,7 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
     <uses-permission android:name="android.permission.NFC" />
+    <uses-permission android:name="android.permission.CAMERA" />
 
     <uses-feature
             android:name="android.hardware.touchscreen"
@@ -57,6 +58,7 @@
                 android:name=".ShadowsocksRunnerActivity"
                 android:process=":bg"
                 android:theme="@android:style/Theme.NoDisplay"
+                android:excludeFromRecents="true"
                 android:launchMode="singleTask">
         </activity>
 
@@ -83,10 +85,18 @@
             </intent-filter>
         </activity>
 
+        <activity
+                android:name=".ScannerActivity"
+                android:label="@string/add_profile_methods_scan_qr_code"
+                android:parentActivityName=".ProfileManagerActivity"
+                android:excludeFromRecents="true"
+                android:launchMode="singleTask"/>
+
         <activity
                 android:name=".AppManager"
                 android:label="@string/proxied_apps"
                 android:parentActivityName=".Shadowsocks"
+                android:excludeFromRecents="true"
                 android:launchMode="singleTask"/>
 
         <activity android:name=".TaskerActivity"