Post fix changes

 - rename barDisable -> barOutOfRange
 - rename Bar.DISABLED -> Bar.OUT_OF_RANGE
 - rename _produce_disabled_bars() -> _produce_out_of_range_bars()
 - rename label Booking not alowed -> Too early to book
 - remove unused sass rule for bar borders
 - remove rule for IE version prior to IE9
 - remove unused import
 - move called to produce_out_of_range_bars() from _produce_candidate_bars()
   to _produce_bars()
 - transform comment into docstring for _produce_out_of_range_bars()