Support for Redmine 4.x

Please consider updateing compatibility to redmine 4.x Trieng to Install this Plugin on redmine 4.0.4 leads to:

***/redmine/plugins# RAILS_ENV=production rake redmine:plugins:migrate
(in /opt/redmine)
rake aborted!
NoMethodError: undefined method `to_prepare' for ActionDispatch::Callbacks:Class
Did you mean?  to_param
/opt/redmine/plugins/msproject_import/init.rb:1:in `<top (required)>'
[...]

1st thing to fix:

In init.rb replace ActionDispatch::Callbacks.to_prepare with: ActiveSupport::Reloader.to_prepare

With this fix the plugin can be integrated

2nd thing to fix:

but redmine is not working due to: (Apache2 log -> Web application could not be started)

undefined method `before_filter' for MsprojImpController:Class
Did you mean?  before_action (NoMethodError)
  /opt/redmine/plugins/msproject_import/app/controllers/msproj_imp_controller.rb:8:in `<class:MsprojImpController>'

this can be replaced by using before_filter in stated file. (found here: https://stackoverflow.com/questions/45015651/undefined-method-for-before-filter)

3rd thing to fix:

Now it shows:

  Message from application: undefined method `after_filter' for MsprojImpController:Class
Did you mean?  after_action (NoMethodError)
  /opt/redmine/plugins/msproject_import/app/controllers/msproj_imp_controller.rb:9:in `<class:MsprojImpController>'

That can be solved by replacing after_filter by after_action

After that he lugin is useable in redmine 4.0.4 Would be happy if someone can confirm.

Maybe Ill do a fork and create a PR with these changes after some tests. Hopefully this project is not dead...

braini75 / msproject_import