Fixing layout of 'contributing' section

Onesixth turned to quarter, better font size for names
Fixing 'about' spelling and sentence structure #23'
Upstream changes
Improving semantics and removing cruft code
Removing duplicate code on Twitter
Refactoring and cleaning up Javascript

Added proper comments to main.js to make it cleaner and more
legible. Moved inline JS from the menu to main.js, reducing repeated
code
Fixing menu to be more semantic and organized

Removing redundant .scroll from menu items, removing redundant
rules in the CSS
Better and clearer .highlight in slider
Simpler and better styles for buttons
Re-indent slider.css
Better delay (5000ms) for slider
Subtle animation for mentors
Subtle animation for students'
Resizing tradzik.jpg to 600x600 from 2200x2200
Making samarjeet.jpg perfectly square
Making bens.jpg perfectly square
amirul.jpg to 600x600 from 1270x1270
Merge remote-tracking branch 'upstream/master'
Removing twitter image and forcing widths of images of .person
Header should be always on the top, increasing z-index of .masthead