luci-app-uhttpd: some fixes because of the lua to javascript porting

* Fix menu path for uhttpd
* Add hint that files could only be uploaded to /etc/luci-uploads
* Rename not knowing enable_delete FileUpload option to enable_remove
* Update ACL list

Signed-off-by: Ayushman Tripathi <ayushmantripathi7724@gmail.com>
Improvement of the commit title and description
Signed-off-by: Florian Eckert <fe@dev.tdt.de>