Merge pull request #117 from yuvale/master

Add an introduction/training feature, using Bootstrap Tour
Some touchups to the tour integration
fix tour's CSS
Tour styling & localization fixes.

- Fixed null step attributes overriding step defaults.
  Bootstrap Tour uses $.extend, which ignores undefined values but
  not null values.
  Internally, null placement causes bootstrap to not add a placement
  class to the tooltip. This caused steps with null position to have
  no arrow displayed.
- Fixed the End button location.
- Translated Pause and Resume.