fix(sparklines): safari bug, spacing, variants

This commit includes the following changes:

* fixes the way the sparkline-chart retrievs it's values for the given
  color variant.

* removes the padding of the item that displays the last value in the
  chart and adds a margin-left instead.  This will allow the consumer
  to change the spacing.

* fixes safari issue that prevented the line from rendering by enabling
  the line animation.