fully JSON based attachment configuration

[sheppard]

Move the attachmentTypes configuration from being JavaScript hardcoded in wq/app.js to JSON embedded in the the wq configuration object.

For example,

var attachmentTypes = {
    relationship: {
        'predicate': 'related',
        'type': 'relationshiptype',
        'getTypeFilter': function(page, context) {
            /* jshint unused: false */
            return {'from_type': page};
        },
        'getChoiceList': function(type, context) {
            /* jshint unused: false */
            return type.to_type;
        },
        'getChoiceListFilter': function(type, context) {
            /* jshint unused: false */
            return {};
        },
        'getDefaults': function(type, context) {
            /* jshint unused: false */
            return {
                'type_label': type.name,
                'to_type': type.to_type
            };
        }
    }
};

might become:

{
    "pages": {
        "relationship": {
            "name": "relationship",
            "url": "relationships",
            "list": true,
            "parents": {
                "relationshiptype": [
                    "type"
                ]
            },
            "children": [],

            "attachment": {
                "predicate": "related",
                "type": "relationshiptype",
                "typeFilter": {
                    "from_type": "{{page}}"
                },
                "choiceListPage": "{{type.to_type}}",
                "choiceListFilter": {},
                "getDefaults": {
                    "type_label": "{{type.name}}",
                    "to_type": "{{type.to_type}}",
                }
          }
    }
}

[sheppard]

Also, the attachmentTypes configuration is redundant with, and should likely replace, the children configuration. (See e.g. 849457c).

[sheppard]

This is essentially done. The children, attachmentTypes, parentFilters, parents, and choices configurations have been merged into a single XLSForm-style field list.