add screenshot image

Delete screenshot.jpg

Update README.md

Update README.md

optimized images and added screenshot

worked on 'input of type number' issue not showing placeholder on firefox

added an alert box when the form is submitted

optimized the images

worked on the form validation to change the <b> to <span>

added form validation

added new images to the page

added some option for the slider

added flexslider js and created a slider

Added the responsive mixin

added sticky menu and worked on main.js