Support pre-HC style account shortcuts

Account shortcuts used to point at MessageList directly with a
content://com.android.email.provider/account/ACCOUNT-UUID URI.

Hook these intents and open Welcome instead.

On Eclair and before, we stored an account-ID directly as an extra,
but this style is no longer supported.

Bug 4208879

Change-Id: I9fecb0723743377a6d7c7e84626e8613f2356492
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 06f5f20..6aaa8e5 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -256,6 +256,14 @@
             </intent-filter>
         </activity>
 
+        <activity
+            android:name=".activity.MessageList"
+            >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+            </intent-filter>
+        </activity>
+
         <receiver
             android:name=".service.AttachmentDownloadService$Watchdog"
             android:enabled="true"/>