Ask for user action after uploading

[TehPeGaSuS]

Currently, after uploading a file, the link is automatically sent to the channel.

This is a bit "risky" because we can have pasted in the wrong channel or we might even regret of uploading the file and currently there's not way to remove it.

What I suggest is:

• Paste the URL on the input field and the user has to hit Enter in order to send it
  or
• After uploading the file, present a box like the one that's used to choose the file to be uploaded (perhaps reuse the same box?) with a Close and Copy URL buttons