switch between docs and wiki layout

Closes #60

core/api/entity/objects.go

@@ -152,6 +152,7 @@ type Document struct {
 	Slug     string `json:"-"`
 	Tags     string `json:"tags"`
 	Template bool   `json:"template"`
+	Layout   string `json:"layout"`
 }
 
 // SetDefaults ensures on blanks and cleans.
@@ -161,6 +162,8 @@ func (d *Document) SetDefaults() {
 	if len(d.Title) == 0 {
 		d.Title = "Document"
 	}
+
+	d.Layout = "doc"
 }
 
 // Attachment represents an attachment to a document.