add share facebook and share twitter
some css fixes
fixes #67 Hide unlinked buttons
fixes #66 : Resizing window breaks zoomed camera ratio
remove unlinked buttons from tutorial mode
really center zoomed cam (not with a fake -66% margin-left)
center cameras on window resize
Merge pull request #1 from Paulloz/roomscss

Rooms CSS
facebook link to share is now dynamic
[database] move database code in common/
[sessions] can configure session store in configuration file
[sessions] use configured session store to store express' sessions
add sessions storing dependencies and repository to package.json
[database] fix redis' get on undefined id
[database] fix some ID problems with databases
fix shitty behavior introduced by ping pong
fixes #22 remove console.log
change script order
auto zoom stream when no one is displayed and receiving a new feed, fixes #74
[sessions] rename session storage collection