Merge branch...

Merge branch '3225-ace-editor-causing-404-errors-every-time-you-try-to-edit-a-file-in-the-webui' into 'master'

Fix Ace syntax highlighting with compiled assets

## What does this MR do?

Update ACE to 4.1.0 to allow modes (syntax highlighting files for particular languages) to be lazily loaded.

## Are there points in the code the reviewer needs to double check?

Don't think so.

## Why was this MR needed?

Syntax highlighting in the file editor only worked in development and test modes, not in production!

## What are the relevant issue numbers?

Closes #3225.

## Screenshots (if relevant)

First, the test setup - add these lines to `development.rb`:
```ruby
  config.assets.debug = false
  config.assets.compile = false
  config.assets.digest = true
```

Then, before starting the server, run `bundle exec rake assets:clobber assets:precompile`.

Before:

![image](/uploads/486198e273019f8969d2e90560d82928/image.png)

There is an error in the console because `/assets/ace/mode-ruby.js` was not found (it's only available when assets are compiled on demand).

After:

![image](/uploads/6aa0d69b7efdfd6fe6aa22b9a49e9716/image.png)

This loads `/assets/ace/mode-ruby-3915f95a6cc47306b1305e4dcb7aca25b2ef9c49b18ec6011707135b6575d8f3.js`, which works because the precompile step included it and told ACE where to find it.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - ~~Added for this feature/bug~~
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5501

CHANGELOG

@@ -70,6 +70,7 @@ v 8.11.0 (unreleased)
   - Update version_sorter and use new interface for faster tag sorting
   - Optimize checking if a user has read access to a list of issues !5370
   - Store all DB secrets in secrets.yml, under descriptive names !5274
+  - Fix syntax highlighting in file editor
   - Nokogiri's various parsing methods are now instrumented
   - Add archived badge to project list !5798
   - Add simple identifier to public SSH keys (muteor)

Gemfile

@@ -201,7 +201,7 @@ gem 'licensee', '~> 8.0.0'
 gem 'rack-attack', '~> 4.3.1'
 
 # Ace editor
-gem 'ace-rails-ap', '~> 4.0.2'
+gem 'ace-rails-ap', '~> 4.1.0'
 
 # Keyboard shortcuts
 gem 'mousetrap-rails', '~> 1.4.6'

Gemfile.lock

@@ -2,7 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     RedCloth (4.3.2)
-    ace-rails-ap (4.0.2)
+    ace-rails-ap (4.1.0)
     actionmailer (4.2.7.1)
       actionpack (= 4.2.7.1)
       actionview (= 4.2.7.1)
@@ -798,7 +798,7 @@ PLATFORMS
 
 DEPENDENCIES
   RedCloth (~> 4.3.2)
-  ace-rails-ap (~> 4.0.2)
+  ace-rails-ap (~> 4.1.0)
   activerecord-session_store (~> 1.0.0)
   acts-as-taggable-on (~> 3.4)
   addressable (~> 2.3.8)

app/assets/javascripts/application.js

@@ -26,7 +26,7 @@
 /*= require bootstrap/tooltip */
 /*= require bootstrap/popover */
 /*= require select2 */
-/*= require ace/ace */
+/*= require ace-rails-ap */
 /*= require ace/ext-searchbox */
 /*= require underscore */
 /*= require dropzone */