Filter additional secrets from Rails logs

Upon inspection of logs, there were a number of fields not filtered. For example:

* authenticity_token: CSRF token
* rss_token: Used for RSS feeds
* secret: Used with Projects::UploadController

Rails provides a way to match regexps, so we now filter:

* Any parameter ending with `_token`
* Any parameter containing `password`
* Any parameter containing `secret`