FIX: 🐛 upload on IE9 wasn't working :'(

- FIX: make sure we set a default name to a pasted image only on Chrome (the only browser that supports it)
- FIX: use ".json" extension to uploads endpoints since IE9 doesn't pass the correct header
- FIX: pass the CSRF token in a query parameter since IE9 doesn't pass it in the headers
- FIX: display error messages comming from the server when there is one over the default error message
- FIX: HACK around IE9 security issue when clicking a file input via JavaScript (use a label and set `visibility:hidden` on the input)
- FIX: hide the "cancel" upload on IE9 since it's not supported
- FIX: return "text/plain" content-type when uploading a file for IE9 in order to prevent it from displaying the save dialog
- FIX: check the maximum file size on the server 💥
- update jQuery File Upload Plugin to v. 5.42.2
- update JQuery IFram Transport Plugin to v. 1.8.5
- update jQuery UI Widget to v. 1.11.1

app/controllers/uploads_controller.rb

@@ -4,17 +4,17 @@ class UploadsController < ApplicationController
 
   def create
     file = params[:file] || params[:files].first
-
     filesize = File.size(file.tempfile)
     upload = Upload.create_for(current_user.id, file.tempfile, file.original_filename, filesize, { content_type: file.content_type })
 
-    if current_user.admin?
+    if upload.errors.empty? && current_user.admin?
       retain_hours = params[:retain_hours].to_i
-      if retain_hours > 0
-        upload.update_columns(retain_hours: retain_hours)
-      end
+      upload.update_columns(retain_hours: retain_hours) if retain_hours > 0
     end
 
+    # HACK FOR IE9 to prevent the "download dialog"
+    response.headers["Content-Type"] = "text/plain" if request.user_agent =~ /MSIE 9/
+
     if upload.errors.empty?
       render_serialized(upload, UploadSerializer, root: false)
     else