Add widget preview

* Also bumped email version number to 3.0 because the version# may need
  to increment to force refresh of the preview tile.

Bug: 3277453
Change-Id: Ic556e49a4b531fcfdbf3c8f6a2537a34ee0f3c63

AndroidManifest.xml

@@ -16,7 +16,10 @@
 
 <manifest
     xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.android.email">
+    package="com.android.email"
+    android:versionCode="300000"
+    android:versionName="3.0"
+    >
 
     <original-package
         android:name="com.android.email" />

res/xml/widget_info.xml

@@ -18,5 +18,6 @@
     android:minWidth="220dp"
     android:minHeight="220dp"
     android:updatePeriodMillis="0"
-    android:initialLayout="@layout/widget" >
-</appwidget-provider>
+    android:initialLayout="@layout/widget"
+    android:previewImage="@drawable/email_widget_preview"
+    />