Cleanup and refactor guided by Android Studio's code analysis.
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index c81e0f8..5ed9453 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -1,24 +1,27 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.fairphone.updater"
-    android:versionCode="14"
-    android:versionName="14 (FP 1.8.2)" >
+          xmlns:tools="http://schemas.android.com/tools"
+          package="com.fairphone.updater"
+    android:versionCode="15"
+    android:versionName="15 (FP 1.8.2)" >
 
     <uses-sdk
         android:minSdkVersion="17"
-        android:targetSdkVersion="17" />
+        android:targetSdkVersion="21" />
 
     <uses-permission android:name="android.permission.ACCESS_SUPERUSER" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
-    <uses-permission android:name="android.permission.REBOOT" />
+    <uses-permission android:name="android.permission.REBOOT"
+                     tools:ignore="ProtectedPermissions"/>
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.READ_PHONE_STATE" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
-    <uses-permission android:name="android.permission.ACCESS_CACHE_FILESYSTEM" />
+    <uses-permission android:name="android.permission.ACCESS_CACHE_FILESYSTEM"
+                     tools:ignore="ProtectedPermissions"/>
     <uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER_ADVANCED" />
 
     <application
@@ -76,10 +79,10 @@
             android:screenOrientation="portrait"
             android:launchMode="singleTop" >
             <intent-filter>
-				<action android:name="android.intent.action.VIEW"></action>
-				<category android:name="android.intent.category.DEFAULT"></category>
-				<category android:name="android.intent.category.BROWSABLE"></category>
-				<data android:host="beta" android:scheme="fairphone"></data>
+				<action android:name="android.intent.action.VIEW"/>
+				<category android:name="android.intent.category.DEFAULT"/>
+				<category android:name="android.intent.category.BROWSABLE"/>
+				<data android:host="beta" android:scheme="fairphone"/>
 			</intent-filter>
         </activity>
     </application>