edx/edx-platform — pull request #5716 by wedaly (2014-10-24 15:03:54+00:00)
Title: Add field from server to set custom error messages for logistration fields

@AlasdairSwan The new output will look like this:
```
{
"method": "post",
"submit_url": "/submit",
"fields": [
{
...
"restrictions": {},
"errorMessages": {
"required": "This field is required!"
},
},
]
}
```