make "Current Version Code" default to most recent APK

closes #36 https://gitlab.com/fdroid/fdroidserver/issues/36

fdroidserver/metadata.py

@@ -132,7 +132,7 @@ class App():
         self.UpdateCheckName = None
         self.UpdateCheckData = None
         self.CurrentVersion = ''
-        self.CurrentVersionCode = '0'
+        self.CurrentVersionCode = None
         self.NoSourceSince = ''
 
         self.id = None

fdroidserver/update.py

@@ -1284,6 +1284,8 @@ def main():
             if app.Name is None:
                 app.Name = bestapk['name']
             app.icon = bestapk['icon'] if 'icon' in bestapk else None
+            if app.CurrentVersionCode is None:
+                app.CurrentVersionCode = str(bestver)
 
     # Sort the app list by name, then the web site doesn't have to by default.
     # (we had to wait until we'd scanned the apks to do this, because mostly the