Set FlickrPhotosActivity as launcher activity, and fixed the layout of photos grid view

app/src/main/AndroidManifest.xml

@@ -12,7 +12,7 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.LiveLikeAndroidChallenge">
         <activity
-            android:name=".AppTestActivity"
+            android:name="com.livelike.flickersearchlibrary.ui.FlickrPhotosActivity"
             android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

flickersearchlibrary/src/main/res/layout/activity_flickr_photos.xml

@@ -21,6 +21,7 @@
         android:id="@+id/gridView"
         android:layout_width="match_parent"
         android:layout_height="0dp"
+        app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/searchView" />