Step 19 - Change the grid buttons to 'medium' scale and add a FontAwesome glyph for each button.

 - Note 1: to add the FontAwesome stylesheet, add the path found in the FontAwesome Getting Started guide (http://fortawesome.github.io/Font-Awesome/get-started/) to the "css" section of our app.json file and set the 'remote' config to true (optionally you can download and host the fonts yourself)
 - Note 2: to find out the charCode for each glyph, use the FontAwesome Cheat Sheet (http://fortawesome.github.io/Font-Awesome/cheatsheet/)
Step 20 - Do some basic theme customizations by changing the base color of the theme to a shade of gray and changing the default font-family and font-size.  Make sure to build the app to see the changes by running 'sencha app build' or 'sencha app build testing' if you want an non-minified version of the generated css.  You can also run 'sencha app watch' to have Sencha Cmd do builds automatically for you.
Changed the proxy for the sessions store to pull from the test json file so this example will work when downloaded and updated the Readme.md file.