New light theme for ES options page

- Updated the options menu for ES, rebuilding it from the ground up using Bootstrap3 as a framework and other HTML5 elements, overall using a light theme instead of the original dark theme. Now, more easier on the eyes and easier to read. 
- All JS remains the same with some additions, allowing for a fixed navbar at the top and smooth-scrolling anchors. 
- The id's and the majority of the classes remain the same in the HTML document and all the CSS classes have been remade from scratch. 
- Added a new logo for ES using blue instead of green and a new font family, using Gotham. 
- Changed the checklist style to be custom and the same on all computers/browsers. Using a new, free, open-source font for the base of the page called Open Sans, which looks better than Arial. 
- Customised the dropdown boxes with blue borders and a blue down arrow.