When send all forms with null the tahiti.js lib crashes

[mgonc]

When send all forms with null as value, the backend don't save this information and when the workflow is requested, it sends the workflow like this:

{
  created: "2018-03-27T19:00:17+00:00",
  description: "",
  enabled:true,
  flows: [],
  id: 79,
  image: "img0.jpg",
  tasks: [
    {
     id: "ea0845ea-e5be-4ce5-bc20-0c339912ddc8", 
     name: "Aggregation 1",
     forms: {}
...
}
 

with this forms inside task empty, the tahiti.js lib crashes.

[waltersf]

Fixed