Multiple fixes in the program of bigdata track

Linked properly speakers with talks.
Track owner picture for valeriu-caraulean. Also few fixes in bio
Merge pull request #14 from vcaraulean/fixes/program-bigdata

Multiple fixes in the program of bigdata track
Merge pull request #16 from vcaraulean/fixes/vcaraulean-bio-and-pic

Track owner's picture for valeriu-caraulean. Also few fixes in bio.
romain-sempe (photo) update.
filip-wojcieszyn (photo) update.
geraud-de-laval (photo) update.
valeriu-caraulean photo update.
Published second sessions speakers biography.
Bugfix for url without http at beginning.
Add email for 2nd speakers
geraud-de-laval second speaker
Some second speakers bio update
romain-sempe update as speaker
filip-wojcieszyn (website url) update.
sam-brannen (photo) update.
julien-jakubowski (photo) update.
maksym-dovgopolyi (photo) update.
julien-jakubowski update.
dominic-williams update.