revision/redesign of conv_item.tpl

this is some major changes to conv_item.tpl
it's not finished yet but you'll get the idea...

most prominent changes:
- get rid of comment indent (inspired by tobias suggestion)
- item title at the top (also inspired by tobias suggestion)
- move photo menu to bootstrap dropdown menu (bottom right now)
- like buttons moved to the right
- like indicators to the left (TODO: i would like the like-list to become a dropdown aswell but this needs a rewrite of format_like() basically two smarty variables are needed - one for the list and one for the button text. maybe mike can give me some support on that?)
- the item backgrounds are now transparent to make it work better with background images/colors (some more work todo here too...)
- default radius to 4px (since every bootstrap item has got a radius)

i think thats about it...