I don't have enough knowledge to support the devices, however i'm trying to help. I've two nexus 4 for testing.
i've modified the devices.json for the mako like the hammerhead section
{
"names": [ "mako" ],
"ubuntu_touch": {
"enabled": true,
"base_url": "http://system-image.ubports.com"
},
"official": true,
"devices": [