Show custom fields in "Relationships" tab
Show custom fields in "Relationships" tab

Fixes a problem where the custom fields cannot be displayed when setting the group of a field to `relationships`.

```
my:
    fields:
        foobar:
            label: Foo Bar
            type: checkbox
            group: relations
```
HonzaMikula/masivnipostele,lenvanessen/bolt,romulo1984/bolt,HonzaMikula/masivnipostele,bolt/bolt,GawainLynch/bolt,romulo1984/bolt,nikgo/bolt,joshuan/bolt,bolt/bolt,electrolinux/bolt,romulo1984/bolt,nikgo/bolt,romulo1984/bolt,joshuan/bolt,bolt/bolt,joshuan/bolt,HonzaMikula/masivnipostele,nikgo/bolt,Intendit/bolt,electrolinux/bolt,Intendit/bolt,GawainLynch/bolt,joshuan/bolt,nikgo/bolt,HonzaMikula/masivnipostele,lenvanessen/bolt,lenvanessen/bolt,electrolinux/bolt,Intendit/bolt,electrolinux/bolt,GawainLynch/bolt,GawainLynch/bolt,Intendit/bolt,lenvanessen/bolt,bolt/bolt