[Polls] Initial import

This application allows to create polls of 5 types:

• simple choice
• multiple choice, with the possibility of limiting the number of choices per voter
• multiple weighted choice, with the possibility of limiting the number of choices per voter: users can assign weights to the options, and the weights need to sum up to 100%
• rating: users are asked assign ratings from 0 to MAX to all the options
• ranking: users are asked to order the options (higher = better)

Poll results are displayed both as a chart and as a summary table.

Additionally, it provides a Poll wiki macro allowing to display the results of a poll in another wiki page.