Fix tiny grammar error
Added in a couple lines that allow for h1 and h2 to be undone when a selection is an h1 or h2 and the button is clicked, similar to the functionality of the bold, italics and underline buttons
On line 336 there was a console.log('clear'), it's been removed
Update jquery.notebook.js

Edited double quotations to be single quotations to keep with the style.
Merge pull request #41 from TrevorHinesley/bug/removed_console_log

Thanks!
Merge pull request #38 from cbartlett/master

You are a native speaker. I'm trusting you ;)
Merge pull request #40 from TrevorHinesley/feature/h1_h2_undo_on_button_click

H1 and H2 can now be undone on button click. Fixes #31