- move charts to the new chart component.
- chart editor component.
- fix ths visualization update process.
- add new fields to visualization table/class (chartData & others).
- add icons to list items.
- make the entity-form and datasource components embeddable
- a basic version of the collect process is implemented.
- display the visualization's thumbs using gridster
- support all the file types supported by d3.

Signed-off-by: Kamal Farsaoui <elfa.kamal@gmail.com>
- generic chart.
- collect-spread extention.
- fix some symfony2 issues (it considers blank values as null).
- fix null color issue in chart-editor.
- constants

Signed-off-by: Kamal Farsaoui <elfa.kamal@gmail.com>