Add an explicit Docker image for JavaScript because of its atypical naming.

lowjoel · lowjoel · commit bdbacfc5f635 · 2016-04-03T17:24:12.000+08:00
diff --git a/lib/coursemology/polyglot/language/java_script.rb b/lib/coursemology/polyglot/language/java_script.rb
@@ -1,4 +1,4 @@
 class Coursemology::Polyglot::Language::JavaScript < Coursemology::Polyglot::Language
   syntax_highlighter 'javascript'
-  concrete_language 'javascript'
+  concrete_language 'javascript', docker_image: 'javascript'
 end
