Fix SILK-143: Null values in time filter when loading dashboard from gist
Add SILK-142: Help message for each panel
Merge commit 'fb54c12dcae2c338b1550dfc8b5a5a76af86cfba' into tarek-develop

* commit 'fb54c12dcae2c338b1550dfc8b5a5a76af86cfba':
  Add SILK-142: Help message for each panel
  Fix SILK-143: Null values in time filter when loading dashboard from gist