Added wifibox hostname in banner

[olijf]

As you requested: #37
Quite useless, but it was an easy fix.

[peteruithoven]

Nice.
A downside is that this happens once, which means people's custom accesspoint name won't show up. Then again I'm not sure this would be possible. The following comment might suggest we could add something to /etc/profile, which would make it dynamic. https://wiki.openwrt.org/doc/howto/snippets#banner_customization
What I don't really like is that it needs to use a rest api endpoint, out of which then needs to be parsed the value, using grep and cut.
Maybe we could create a small lua script that just prints the hostname and try calling that from /etc/profile?