Ninja Forms - File Uploads Addon 3.3.20

*New:*
* You can now use mergetags in the 'Rename Uploaded File' field setting
* Different mergetags for File Upload fields can now be selected, eg. {field:my_field_key:link}
* New mergetag for the filename of the file, eg. {field:my_field_key:filename}
* New mergetags for when the file has been added to the media library, eg. {field:my_field_key:attachment_url}, {field:my_field_key:attachment_embed}

*Changes:*
* Ability to set Amazon key and secret and other settings as constants: 'NF_FU_AMAZON_S3_ACCESS_KEY' and 'NF_FU_AMAZON_S3_SECRET_KEY'

*Bugs:*
* Nonce error when submitting a form on a page that has been cached
* Fatal error caused when running UpdraftPlus or BackupBuddy plugin

*Changes:*
* Use the external service name not the slug in the uploads browser table
* Make the external service 'Connect' button stand out from the 'Disconnect' button

*Bugs:*
* Fatal error caused when running the EDD Amazon S3 plugin
* Mergetag output blank when running the Conditional Logic plugin

*Bugs:*

* Fatal error when uploading to Dropbox on installs with legacy Dropbox API tokens
* Fatal error due to memory exhaustion on some installs due to large Google SDK