Experience upgrade splash screen.

Behaves similarly to the DatabaseUpgradeActivity. You have a
static list of ExperienceUpgrade models that include a "trigger"
version, where when a user upgrades through it a notification
will appear, and there will be a splash explanation screen.

Right now the splash screens are basic and not too configurable,
but that can be reworked as upgrades demand.

Closes #4151

src/org/thoughtcrime/securesms/BasicIntroFragment.java

@@ -0,0 +1,54 @@
+package org.thoughtcrime.securesms;
+
+import android.os.Bundle;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+public class BasicIntroFragment extends Fragment {
+
+  private static final String ARG_DRAWABLE = "drawable";
+  private static final String ARG_TEXT     = "text";
+  private static final String ARG_SUBTEXT  = "subtext";
+
+  private int drawable;
+  private int text;
+  private int subtext;
+
+  public static BasicIntroFragment newInstance(int drawable, int text, int subtext) {
+    BasicIntroFragment fragment = new BasicIntroFragment();
+    Bundle args = new Bundle();
+    args.putInt(ARG_DRAWABLE, drawable);
+    args.putInt(ARG_TEXT, text);
+    args.putInt(ARG_SUBTEXT, subtext);
+    fragment.setArguments(args);
+    return fragment;
+  }
+
+  public BasicIntroFragment() {}
+
+  @Override
+  public void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    if (getArguments() != null) {
+      drawable = getArguments().getInt(ARG_DRAWABLE);
+      text     = getArguments().getInt(ARG_TEXT    );
+      subtext  = getArguments().getInt(ARG_SUBTEXT );
+    }
+  }
+
+  @Override
+  public View onCreateView(LayoutInflater inflater, ViewGroup container,
+                           Bundle savedInstanceState) {
+    View v = inflater.inflate(R.layout.color_fragment, container, false);
+
+    ((ImageView)v.findViewById(R.id.watermark)).setImageResource(drawable);
+    ((TextView)v.findViewById(R.id.blurb)).setText(text);
+    ((TextView)v.findViewById(R.id.subblurb)).setText(subtext);
+
+    return v;
+  }
+}