Magnet button on the view

Exposing the magnet on the view, right next to the download torrent button.

A new PR is coming up from @nimiq, we want to show the link directly while hovering in the magnet button.

In other words, instead of:

```
http://localhost:8080/data/magnet/3/
```

we want to see:

```
magnet:?xt=urn:btih:4bdcd0009a04045ef84208364542e27f65a29d54&dn=derby.log.torrent&tr=http://localhost:8080/data/announce
``` 

When hovering over the link in the view.