Polishing the buttons on the page

Converted the page buttons to using button tag instead of input. Also added the bootstrap classes to the button tags and added pertinent icons for the buttons.
Removing a spurious end tag
Updating CSS for margins

Added a 10 px margin to make sure that buttons don't collide with the banners
Top margin for diagram action button

Made sure that the diagram top button doesn't collide with the header
Merge pull request #5 from rohanranade/master

Minor modifications and styling to the buttons on the site to make them more bootstrap-like