Uses the vis api to retrieve the list of tables. The tables are still created using the table collection
Fixes specs.
Removed Mapbox Light and MapBox Warden. Added new styles for GMaps Gray Roadmap. Updated basemap dropdown: now we show 4 elements per column. Changed copy for initial state of the dropdown
Merge branch 'develop' of github.com:CartoDB/cartodb20 into develop

* 'develop' of github.com:CartoDB/cartodb20:
  Fix filter in Table#visualizations
  call #copy on Visualization::Copier when copying a visualization