Twitter support!

This allows to submit your twitter profile to submissions and interests (82778f3)

We also got a tweet-about button after the creation of a talk/interest. It is cookie based like votes. (fc78203
)

this needs #34 and #33 (hapi updates) and #37 (XSS, filtering) merged before, they are included in this optimistic branch
I was a little confused about wether or not to include the @ here. (At this point I didn't know, that it does not matter :))
I thought about adding the @ as pre-populated value or as label, so users don't have to guess.
What's your take on this? :)