Fix alignment of variations in test-app (#90)

Author: elliotykim

test-app/images/demo-app-flow.png

@@ -50,7 +50,6 @@
         android:layout_marginTop="-20dp"
         android:layout_marginBottom="30dp"
         android:layout_centerVertical="true"/>
-
     <fragment
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"

test-app/src/main/res/layout/activity_variation_a.xml

@@ -19,19 +19,15 @@
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/activity_variation_b"
-    android:background="#FFFFFF"
+    android:background="@drawable/ic_background_varib_marina"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:paddingBottom="@dimen/activity_vertical_margin"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
+    android:gravity="center_vertical"
     tools:context="com.optimizely.ab.android.test_app.VariationBActivity">
-    <ImageView
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:background="@drawable/ic_background_varib_marina"
-        />
     <TextView
         android:id="@+id/tv_variation_b_text_1"
         android:layout_width="wrap_content"