Added MIME types library for static file serving

lib/landline/probe/serve_handler.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative "../probe"
+require_relative "../util/mime"
 
 module Landline
   module Handlers
@@ -18,12 +19,18 @@ module Landline
       # Method callback on successful request navigation.
       # Tries to serve files matched by handler
       # @param request [Landline::Request]
-      # @return [Boolean] true if file was found
+      # @return [Boolean, Array] true if file was found
       def process(request)
         path = File.expand_path(request.filepath)
         return unless path.start_with? @properties["path"]
 
-        File.open(path.delete_suffix("/"))
+        filepath = path.delete_suffix("/")
+
+        [200,
+         {
+           "content-type" => Landline::MIME.get_mime_type(filepath)
+         },
+         File.open(filepath)]
       rescue StandardError
         false
       end