Allow configuration of the prop which the model gets passed to.

Previously the model was passed to 'value' without anyway to change it, 
but now it can be defined using the property `valueProp` on the root of 
the field, or setting the property in the options prop to the 
vue-form-json-schema component.

Author: jarvelov

src/vfjs-component/methods/getters.js

@@ -54,6 +54,10 @@ const getters = {
       key: this.vfjsFieldId,
     };
 
+    const valueProp = {
+      [this.vfjsFieldValueProp]: this.vfjsFieldModel,
+    };
+
     const allAttributes = merge(
       {},
       key,
@@ -62,6 +66,7 @@ const getters = {
       fieldOptionsAsProps,
       options,
       computedOptions,
+      valueProp,
     );
 
     return allAttributes;

src/vfjs-component/props.js

@@ -61,6 +61,9 @@ const props = {
     type: Object,
     required: true,
   },
+  vfjsFieldValueProp: {
+    type: String,
+  },
   vfjsOptions: {
     type: Object,
     required: true,

src/vfjs-global/data.js

@@ -41,6 +41,7 @@ const data = () => ({
     validate: true,
     validateOnLoad: true,
     validateOnChange: true,
+    valueProp: 'value',
   },
   vfjsSchema: {},
   vfjsState: {},

src/vfjs-global/methods/vfjs-helpers/index.js

@@ -12,6 +12,7 @@ const vfjsHelpers = {
       fieldOptions: vfjsFieldOptions = {},
       model: vfjsFieldModelKey = '',
       required: vfjsFieldRequired = false,
+      valueProp: vfjsFieldValueProp = this.vfjsOptions.valueProp,
     } = vfjsFieldUiSchema;
 
     const vfjsFieldSchema = this.getVfjsFieldSchema(vfjsFieldModelKey) || {};
@@ -48,6 +49,7 @@ const vfjsHelpers = {
       vfjsFieldSchemas,
       vfjsFieldState,
       vfjsFieldUiSchema,
+      vfjsFieldValueProp,
       vfjsOptions: this.vfjsOptions,
       vfjsModel,
       vfjsState,