Add m4v video support

WebsiteGenerator/Files/MediaType.swift

@@ -8,19 +8,22 @@ private let supportedImageExtensions: [String : NSBitmapImageRep.FileType] = [
 ]
 
 private let supportedVideoExtensions: Set<String> = [
-    "mp4", "mov"
+    "mp4", "mov", "m4v"
 ]
 
 enum MediaType {
     case image
     case video
     case file
+    case svg
 
     init(fileExtension: String) {
         if supportedImageExtensions[fileExtension] != nil {
             self = .image
         } else if supportedVideoExtensions.contains(fileExtension) {
             self = .video
+        } else if fileExtension == "svg" {
+            self = .svg
         } else {
             self = .file
         }

WebsiteGenerator/Files/VideoType.swift

@@ -2,11 +2,14 @@ import Foundation
 
 enum VideoType: String {
     case mp4
+    case m4v
 
     var htmlType: String {
         switch self {
         case .mp4:
             return "video/mp4"
+        case .m4v:
+            return "video/mp4"
         }
     }
 }