dhcp: fix Cisco 7937G line

Reviewed-by: https://github.com/apps/wazo-zuul

WAZO-1446: fix NAT for Yealink phones

Reviewed-by: https://github.com/apps/wazo-zuul

reason: keep-alives were not sent.

WAZO-1233: fix language files for Yealink v84

Reviewed-by: https://github.com/apps/wazo-zuul

reason: issue with HTTP headers causes ghost devices

add zuul support

Reviewed-by: https://github.com/apps/wazo-zuul

reason: older firmware versions used hyphens in the model name

WAZO-1378: Add Fanvil X phones