Remove the whole local/remoteConfigured settings

We now infer this by checking if the directory exists, and by reading
the git config. It's a bit slower, but it's a far better method. I can
add a cache later, if it turns out to be too slow.

lib/appstate.dart

@@ -18,4 +18,6 @@ class AppState {
 
   NotesFolderFS notesFolder;
   var gitBaseDirectory = "";
+
+  bool remoteGitRepoConfigured = false;
 }