added the classes to the cards
added button style orange to the mixins
improved button class with the global button orange
added the classes and style to the cards items
added the sprite to the cards
improved style in the cards items
fixed data-value in order to estimate the task
Merge branch 'improve-cards-style'

* improve-cards-style:
  fixed data-value in order to estimate the task
  improved style in the cards items
  added the sprite to the cards
  added the classes and style to the cards items
  improved button class with the global button orange
  added button style orange to the mixins
  added the classes to the cards
cloused attribute does not exist any more