Manage Update Site dialog: improve user-friendliness

[hinerm]

The Manage Update Sites dialog has little chance of being fully understood without external resources. I think we can do three things to improve user experience:

1. Rename Host column to something along the lines of Username, Uploader, Upload Username.
2. Remove Directory on Host column
   • Or hide it by default and provide a toggle button to show it
3. Remove the need for webdav: from Host column cells. For any core update site the protocol will always be webdav so we can programmatically prepend it. This is also more future-proof if we change the protocol.
   • Alternatively, these cells could prompt the user with a multiple-choice/combo box of available protocols. But I think this is giving the user an unnecessary decision in most cases.

[hinerm]

@ctrueden do you see any problems with these suggestions?

[imagejan]

@hinerm wrote:

Remove the need for webdav: from Host column cells.

We have an internal update site using sftp in our institute. As long as explicitly providing the protocol still works, I'm fine with the changes you propose. (Directory on host would also be required in this case, because it can be any folder on an ftp server.)