[scss] button gradients and mixins
[scss] rm bootstrap buttons
[scss] themable follow button
[scss] themable register button
[scss] themable feedback button
[scss] refactor buttons
[scss] remove duplicate button definitions from _forms.scss
[scss] fix delegate button vertical align
[scss] rm unused images
[scss] refactor tutorial
[scss] refactor subnav
[scss] recreate original subnav current tab styling
use button_round in pager filter box
[scss] set button min-width
fixup [scss] button gradients and mixins
[scss] fix submit button font-size
[scss] set register button min-width
pep8
fixup [scss] button gradients and mixins
Fix submit button height and right margin

See discussion in #473.