bump sdk to 22, update notifications

Notification updates include:

1) Setting theme colors
2) Using high-res contact photos
3) Updating the notification icon to latest

Closes #2935
Fixes #2923
Fixes #2732
Fixes #2548

// FREEBIE

res/values/dimens.xml

@@ -9,6 +9,7 @@
     <dimen name="transport_selection_popup_width">200sp</dimen>
     <dimen name="transport_selection_popup_xoff">0dp</dimen>
     <dimen name="transport_selection_popup_yoff">1dp</dimen>
+    <dimen name="contact_photo_target_size">64dp</dimen>
     <dimen name="contact_selection_photo_size">50dp</dimen>
     <dimen name="thumbnail_max_size">230dp</dimen>
     <dimen name="preference_fragment_padding_side">8dp</dimen>

res/values/strings.xml

@@ -435,8 +435,8 @@
     <string name="KeyCachingService_lock">Lock with passphrase</string>
 
     <!-- MessageNotifier -->
-    <string name="MessageNotifier_d_new_messages">%d new messages</string>
-    <string name="MessageNotifier_most_recent_from_s">Most recent from: %s</string>
+    <string name="MessageNotifier_d_messages_in_d_conversations">%1$d messages in %2$d conversations</string>
+    <string name="MessageNotifier_most_recent_from_s">Most recent from: %1$s</string>
     <string name="MessageNotifier_encrypted_message">Encrypted message...</string>
     <string name="MessageNotifier_media_message_with_text">Media message: %s</string>
     <string name="MessageNotifier_no_subject">(No subject)</string>