Toggle the legend when the layers are hidden/visible
Updates the legend indicator when toggling the visibility of the layers in the share dialog
Merge branch 'release/staging' of github.com:CartoDB/cartodb into release/staging

* 'release/staging' of github.com:CartoDB/cartodb:
  Update Asset model specs
  Add kind attribute to Asset model
  Tries to set the original file name when uploading assets to S3