Allow non-markdown content in content directory

Allow content that is not markdown and does not need to be rendered to
exists in the content directory.  Currently any valid html or xml
document can exist.  Templates are applied to these documents as well.
If you need to have content that doesn't have templates or AbsUrlify
like operations, then continue to put this content in static and it will
be copied over.

hugolib/page.go

@@ -90,8 +90,7 @@ func newPage(filename string) *Page {
 	page := Page{contentType: "",
 		File:   File{FileName: filename, Extension: "html"},
 		Node:   Node{Keywords: make([]string, 10, 30)},
-		Params: make(map[string]interface{}),
-		Markup: "md"}
+		Params: make(map[string]interface{})}
 	page.Date, _ = time.Parse("20060102", "20080101")
 	page.guessSection()
 	return &page
@@ -361,6 +360,18 @@ func (p *Page) ExecuteTemplate(layout string) *bytes.Buffer {
 	return buffer
 }
 
+func (page *Page) guessMarkupType() string {
+	if page.Markup != "" {
+		return page.Markup
+	}
+
+	if strings.HasSuffix(page.FileName, ".md") {
+		return "md"
+	}
+
+	return "unknown"
+}
+
 func (page *Page) parse(reader io.Reader) error {
 	p, err := parser.ReadFrom(reader)
 	if err != nil {
@@ -383,11 +394,15 @@ func (page *Page) parse(reader io.Reader) error {
 		}
 	}
 
-	switch page.Markup {
-	case "md":
+	switch page.guessMarkupType() {
+	case "md", "markdown", "mdown":
 		page.convertMarkdown(bytes.NewReader(p.Content()))
 	case "rst":
 		page.convertRestructuredText(bytes.NewReader(p.Content()))
+	case "html":
+		fallthrough
+	default:
+		page.Content = template.HTML(p.Content())
 	}
 	return nil
 }