Inside div#shape-creator, add a select tag
with two options,
Option one:- "Square"
Option one:- "Circle"
The default selcted option being "Square".
And a button with text "Add shape", on which when we click,
the a div with the className(lowercased) as selected option is made and added to
div#shapes-holder.
Ex:- User opens the app, the default selected is "Square", user clicks on add button
div#shapes-holder, a div with class square is added.
User selected "Circle" option, then clicks button then
a div with class circle is added.
Classes are predefined are defined in styles