Implement data visualization options to Voting Portlet

[davilima6]

Portlet creators should be able to choose whether to display votes with numbers, bars or pies - and even not displaying any information about votes at all.

This could be a radio selection list with the default option being inheriting from the choice made on the poll which is actually displayed.

/cc @agnogueira

[hvelarde]

we can analyze this better if @agnogueira can come up with some mockups

[davilima6]

The current behaviour simply falls back to the options defined in the content object.