Fixes vis specs
Fixes creation of a vis from the start_view
Merge branch 'develop' of github.com:CartoDB/cartodb20 into develop

* 'develop' of github.com:CartoDB/cartodb20:
  Identify as dependent visualizations those with several layers that exclusively depend in the same single table
  Return unique elements in Table#affected_visualizations
  Fix
New Vis dialog no longer requires the visualization object