Changes to make appearance lighter on the eye

- Removed bold face from various texts including document titles. Bold
  in document titles should be reserved for hit highlighting.
- Made constraints a smaller font size.
- Changed appearance of sidebar items to be even lighter and changed
  horrible green color from selected facets to black.
- Added labels to document formats. For now this is only
  article => 'Journal article', journal => 'Journal' and book => 'Book'
- Fixed a test that broke after adding format labels.