import: don't crash due to missing id

Fixes #129

fdroidserver/common.py

@@ -1027,7 +1027,7 @@ def app_matches_packagename(app, package):
     if not package:
         return False
     appid = app['Update Check Name'] or app['id']
-    if appid == "Ignore":
+    if appid is None or appid == "Ignore":
         return True
     return appid == package
 

fdroidserver/import.py

@@ -175,6 +175,7 @@ def main():
 
     apps = metadata.read_metadata()
     package, app = metadata.get_default_app_info_list(apps)
+    app['id'] = None
     app['Update Check Mode'] = "Tags"
 
     root_dir = None