refactor and improve contact selection

* unify single and multi contact selection activities
* follow android listview design recommendations more closely
* add contact photos to selection
* change indicator for push to be more obvious
* cache circle-cropped bitmaps
* dedupe numbers when contact has multiple of same phone number

// FREEBIE

res/layout/push_contact_selection_activity.xml

@@ -8,7 +8,7 @@
     <fragment
         xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
         android:id="@+id/contact_selection_list_fragment"
         android:name="org.thoughtcrime.securesms.PushContactSelectionListFragment">
         </fragment>