We do not support forwarding (yet), however there is a workaround in which you can forward your domain on DNS level.
You can forward your domain through DNS with a CNAME record.
A CNAME record forwards your (sub)domain to another (sub)domain.
Please take note that using this method of forwarding prevents other records from being read, since a CNAME takes priority over all other records on that (sub)domain.
So how can you use this as a forward? Let's say you want to forward domainone.com to domaintwo.com. You can use the CNAME like so:
domainone.com CNAME domaintwo.com
However, this means that only domainone.com is forwarded to domaintwo.com. If people go to www.domainone.com they are not forwarded, since subdomains aren't forwarded.
You can remedy this by adding another CNAME:
www.domainone.com CNAME domainone.com
This will make sure the www.domainone.com will be forwarded to domainone.com which in turn will be forwarded to domaintwo.com
Of course you can also forward www.domainone.com to domaintwo.com, but if you ever need to update the forwarder, you'll need to update two records in stead of one.