Add video calling intro screen

// FREEBIE

res/values/strings.xml

@@ -264,6 +264,12 @@
     <string name="ExperienceUpgradeActivity_welcome_to_signal_excited">Welcome to Signal!</string>
     <string name="ExperienceUpgradeActivity_textsecure_is_now_signal">TextSecure is now Signal.</string>
     <string name="ExperienceUpgradeActivity_textsecure_is_now_signal_long">TextSecure and RedPhone are now one app: Signal. Tap to explore.</string>
+
+    <string name="ExperienceUpgradeActivity_say_hello_to_video_calls">Say hello to secure video calls.</string>
+    <string name="ExperienceUpgradeActivity_signal_now_supports_secure_video_calls">Signal now supports secure video calling. Just start a Signal call like normal, tap the video button, and wave hello.</string>
+    <string name="ExperienceUpgradeActivity_signal_now_supports_secure_video_calling">Signal now supports secure video calling.</string>
+    <string name="ExperienceUpgradeActivity_signal_now_supports_secure_video_calling_long">Signal now supports secure video calling. Tap to explore.</string>
+
     <!-- ExportFragment -->
     <string name="ExportFragment_export">Export</string>
     <string name="ExportFragment_export_plaintext_to_storage">Export plaintext to storage?</string>

res/xml/preferences_advanced.xml

@@ -18,7 +18,7 @@
                         android:key="pref_system_emoji"
                         android:title="@string/preferences_advanced__use_system_emoji"
                         android:summary="@string/preferences_advanced__disable_signal_built_in_emoji_support" />
-    
+
     <org.thoughtcrime.securesms.components.SwitchPreferenceCompat
             android:defaultValue="false"
             android:key="pref_turn_only"

src/org/thoughtcrime/securesms/ExperienceUpgradeActivity.java

@@ -1,14 +1,11 @@
 package org.thoughtcrime.securesms;
 
-import android.annotation.TargetApi;
 import android.app.Notification;
 import android.app.PendingIntent;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.drawable.ColorDrawable;
-import android.os.Build;
-import android.os.Build.VERSION_CODES;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.StringRes;
@@ -43,7 +40,15 @@ public class ExperienceUpgradeActivity extends BaseActionBarActivity {
                                                                    R.string.ExperienceUpgradeActivity_textsecure_is_now_called_signal)),
                       R.string.ExperienceUpgradeActivity_welcome_to_signal_excited,
                       R.string.ExperienceUpgradeActivity_textsecure_is_now_signal,
-                      R.string.ExperienceUpgradeActivity_textsecure_is_now_signal_long);
+                      R.string.ExperienceUpgradeActivity_textsecure_is_now_signal_long),
+    VIDEO_CALLS(245,
+                      new IntroPage(0xFF2090EA,
+                                    BasicIntroFragment.newInstance(R.drawable.video_splash,
+                                                                   R.string.ExperienceUpgradeActivity_say_hello_to_video_calls,
+                                                                   R.string.ExperienceUpgradeActivity_signal_now_supports_secure_video_calls)),
+                      R.string.ExperienceUpgradeActivity_say_hello_to_video_calls,
+                      R.string.ExperienceUpgradeActivity_signal_now_supports_secure_video_calling,
+                      R.string.ExperienceUpgradeActivity_signal_now_supports_secure_video_calling_long);
 
     private            int             version;
     private            List<IntroPage> pages;