Redesign frontend

[MichaelCurrin]

• Use bulma for sticky header
• Remove footer
• Use CSS-based Bulma accordions to switch between keywords - avoid having to use droplist or radio and removes need for split between form and result. Note - this only works for tags view.
• Remove chosen keywords from frontend

[MichaelCurrin]

See if repos view and labels view should be separate screens and how to filter by repo or label - do a mockup.

Think about the starred repos view too