remove need for file

app_name.xml's contents are in generated file, so just use that. Saves a
change on each release.

xwords4/android/app/src/main/java/org/eehouse/android/xw4/AboutAlert.java

@@ -56,7 +56,7 @@ public class AboutAlert extends XWDialogFragment {
         String dateString
             = df.format( new Date( BuildConfig.BUILD_STAMP * 1000 ) );
         vers.setText( getString( R.string.about_vers_fmt,
-                                 getString( R.string.app_version ),
+                                 BuildConfig.VERSION_NAME,
                                  BuildConfig.GIT_REV, dateString ) );
 
         TextView xlator = (TextView)view.findViewById( R.id.about_xlator );

xwords4/android/app/src/main/res/values/app_name.xml

@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-
-<resources>
-  <string name="app_version" translatable="false">4.4.116</string>
-</resources>