UI for enabling a private WLAN [WIP]

This pull request contains the package "gluon-luci-wifi" for setting up a private WLAN as requested in freifunk-gluon/gluon#122

I tested it by running my device in config mode and copying the files with scp into to target folder.
`scp -r gluon/gluon-luci-wifi/files root@192.168.1.1:/` I did not created a build yet.