Fix layouts errors and warnings

VectorDrawables could make the app crash or could be badly rendered
under particular circumstances

Change-Id: Id944358ad984e719750ea72e2a01b7b569876d49
Reviewed-by: Philippe Gorley <philippe.gorley@savoirfairelinux.com>
diff --git a/ring-android/app/src/main/res/layout/frag_conversation.xml b/ring-android/app/src/main/res/layout/frag_conversation.xml
index f0e66c2..f8ebf96 100644
--- a/ring-android/app/src/main/res/layout/frag_conversation.xml
+++ b/ring-android/app/src/main/res/layout/frag_conversation.xml
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
@@ -10,8 +11,6 @@
         android:layout_height="match_parent"
         android:layout_alignParentBottom="true"
         android:layout_alignParentEnd="true"
-        android:layout_alignParentLeft="true"
-        android:layout_alignParentRight="true"
         android:layout_alignParentStart="true"
         android:layout_alignParentTop="true"
         android:clipToPadding="false"
@@ -44,8 +43,6 @@
         android:layout_height="wrap_content"
         android:layout_alignParentBottom="true"
         android:layout_alignParentEnd="true"
-        android:layout_alignParentLeft="true"
-        android:layout_alignParentRight="true"
         android:layout_alignParentStart="true"
         android:layout_marginBottom="16dp"
         android:layout_marginLeft="8dp"
@@ -83,8 +80,8 @@
                 android:background="?selectableItemBackgroundBorderless"
                 android:contentDescription="@string/send_message"
                 android:padding="8dp"
-                android:src="@drawable/ic_send_black"
-                android:tint="@android:color/darker_gray" />
+                android:tint="@android:color/darker_gray"
+                app:srcCompat="@drawable/ic_send_black" />
         </LinearLayout>
     </android.support.v7.widget.CardView>
 </RelativeLayout>
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