new banner tile

[hvelarde]

the idea of the banner tile is to replace both image and link tiles following the reasoning exposed on #217.

the banner tile should work like this:

• must accept both, Image and Link objects
• if we drop an image to the tile, we must be able to add a link by editing the tile
• if we drop a link into the tile, we must be able to add an image by editing the tile
• dropping and image after a link, or a link after an image, should first clear the tile information to avoid inconsistencies

[cleberjsantos]

Very nice :P i'm +1