Improve design

Current progress (stable) of redesigning / improving peer assessment page.

Changes include:

• redesign login page
• current assessment card height is same across each row
• tick on completed assessment is moved to top right and scaled to be larger
• landing page is responsive / now compatible for mobile devices
• migrate some w3 features to BootStrap, e.g. cards are grey and without box shadow
• make project information and buttons vertically align
• more margin between cards (see previews)