luci-app-openvpn: "final" changeset

* add 'auth-user-pass' edit section in file mode (see screenshot)
* add port & protocol detection in file mode (see screenshot)
* don't mix file & normal edit modes any longer
* add CC compatibility fix (for turris devices)
* fix/refine JS instance name filter
* remove needless CSS rules
* unlink ovpn/auth files on section removal
* commit changes instantly (Add/Upload/Delete)

Signed-off-by: Dirk Brenken <dev@brenken.org>