Breaking Change to request param

Before:

GET /dir?download shows simple page.

GET /dir?downloadfile shows simple page, and add download param to files.

GET /file?download download a file instead of displaying its content.

GET /file?downloadfile download a file instead of displaying its content.

After:

GET /dir?simple shows simple page.

GET /dir?download add download param to files.

GET /dir?simpledownload shows simple page, and add download param to files.

GET /file?download download a file instead of displaying its content.