Added tachyons stylesheet & updated assessment card styles

Style Merge Request

Motivation and Context

The updates assessment card component reflects the new styling for the app. ![Screen_Shot_2018-07-19_at_6.41.57_AM]

Screenshots, Code, Links

Related Tasks

NB: Logic still needs to be added:

• Assessment Name is not appearing, even though the object is in the markup within the component file.
• Assessee Name object needs to be created
• Status progress bar icons need to change color based on which is active, complete, or incomplete
• Status messages need to change based on which stage the assessment is in
• Buttons are not yet active
• Primary button (which changes depending upon the stage) is not yet active

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