inline ui schema in schema support with x-ui-schema

[jbockle]

instead of explicitly specifying ui schema for a schema, support inlining ui schema in a json schema

i.e.

• from

  var jsonSchema = {
  "type": "string"
  }
  
  var uiSchema = {
  "ui:view": "textbox"
  }

• to

  var jsonSchema = {
  "x-ui-schema": { "ui:view": "textbox" },
  "type": "string"
  }

if a ui schema also exists, ui-schema wins