Fix syntax highlight in some files

_episodes/04-formatting.md

@@ -137,7 +137,7 @@ which is rendered as:
 for thing in collection:
     do_something
 ~~~
-{: .python}
+{: .language-python}
 
 The class specified at the bottom using an opening curly brace and colon,
 the class identifier with a leading dot,

_episodes/06-style-guide.md

@@ -19,6 +19,7 @@ For example, "to delete the cell press <kbd>D</kbd>" should be write as
 ~~~
 to delete the cell press <kbd>D</kbd>
 ~~~
+{: .html}
 
 The table below covers most of the keyboard key labels.
 
@@ -79,5 +80,6 @@ For example, "press <kbd>Ctrl</kbd>+<kbd>X</kbd> to quit nano" should be write a
 ~~~
 press <kbd>Ctrl</kbd>+<kbd>X</kbd> to quit nano.
 ~~~
+{: .html}
 
 {% include links.md %}

setup.md

@@ -55,7 +55,7 @@ new lesson is `data-cleanup`.
     ~~~
     $ git clone -b gh-pages https://github.com/timtomch/data-cleanup.git
     ~~~
-    {: .bash}
+    {: .language-bash}
 
     Note that the URL for your lesson will have your username and chosen repository name.
 
@@ -64,7 +64,7 @@ new lesson is `data-cleanup`.
     ~~~
     $ cd data-cleanup
     ~~~
-    {: .bash}
+    {: .language-bash}
 
     Note that the name of your directory should be what you named your lesson 
     on the example this is `data-cleanup`.
@@ -75,7 +75,7 @@ new lesson is `data-cleanup`.
     ~~~
     $ git remote add template https://github.com/swcarpentry/styles.git
     ~~~
-    {: .bash}
+    {: .language-bash}
 
     This will allow you to pull in changes made to the template,
     such as improvements to our CSS style files.
@@ -87,7 +87,7 @@ new lesson is `data-cleanup`.
     ~~~
     $ git checkout gh-pages
     ~~~
-    {: .bash}
+    {: .language-bash}
 
 	This will ensure that you are using the most "stable" version of the
 	template repository. Since it's being actively maintained by the
@@ -107,7 +107,7 @@ new lesson is `data-cleanup`.
     ~~~
     $ make serve
     ~~~
-    {: .bash}
+    {: .language-bash}
 
 14. Commit your changes *and the HTML pages in the root directory of
     your lesson repository* and push to the `gh-pages` branch of your
@@ -119,7 +119,7 @@ new lesson is `data-cleanup`.
     $ git commit -m "Explanatory message"
     $ git push origin gh-pages
     ~~~
-    {: .bash}
+    {: .language-bash}
 
 15. [Tell us][contact] where your lesson is so that we can add it to
     the appropriate index page(s).