customizable subscribe button placement

- added variable $subscribe-button-placement to control the placement of
  subscribe button. if set to `header` it will place the button on header
  (the previous default). any other value will put it at its normal place.

- use default button style for subscribe button
show .pretty-button only on hover

- hide .pretty-button until link is hovered in link listing
- style for report counter
Merge branch 'subscribe-button-placement'

This should fix #8
darken flair popup in nightmode
darken flair settings in nightmode

also get rid of the stupid green box added recently in reddit stylesheet