Add the Allow Rotation setting to Launcher3.

This CL adds a Settings activity along with the code needed to provide
a "Allow Rotation" setting to all phones and tablets. This setting is
set to false for phones and true for tablets. On changing the setting
from unlocked to locked, the launcher (and the Settings activity)
will get locked to the orientation the user was in when he disabled
"Allow Rotation". This is consistent with how the natural rotation
feature of Android works.

Change-Id: I8a1c59d1fa0bb9262530cad96e0a9bdbab0d9344
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index b61b90c..9d8a76a 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -148,6 +148,12 @@
             </intent-filter>
         </activity>
 
+        <activity
+            android:name="com.android.launcher3.SettingsActivity"
+            android:label="@string/settings_button_text"
+            android:autoRemoveFromRecents="true">
+        </activity>
+
         <!-- Debugging tools -->
         <activity
             android:name="com.android.launcher3.MemoryDumpActivity"