Gravity Forms Dropbox Addon 3.1.2

- Added the [gform_dropbox_should_upload_file](https://docs.gravityforms.com/gform_dropbox_should_upload_file/) filter.
- Updated the minimum Gravity Forms version to 2.0.8.
- Fixed an issue where the upload is attempted again for existing files, if the feed is reprocessed by other add-ons.
- Fixed an issue where files with names that include Chinese characters aren't sent to Dropbox when uploaded via a multi-file enabled File Upload field.

- Added support for OAuth refresh tokens in accordance with changes to the Dropbox API.
- Fixed the ability of custom apps with team permissions to authenticate.
- Fixed an issue where it is not possible to disconnect a custom app if using an access token that has already been deauthorized.
- Fixed the folder display so it is possible to select team folders when using a custom app with team permissions.
- Fixed an issue where an empty space appears under the connect to dropbox button on the settings page.
- Updated the user interface on the Dropbox settings page.
- Updated the user interface of the authorization screen.

- Added accessibility enhancements to the Dropbox upload field.
- Fixed styling of the Dropbox Upload field description to correctly display above or below the input in the editor in Gravity Forms 2.5.
- Fixed an issue where authentication may not complete after attempting a connection with Dropbox.