Change logging system to GLOG

Summary:
Instead of using the boost library wich seems really buggy when I tried to
implement extend features (syslog, files, ...)

Also, we can, now, differenciate two type of log:

 LOG(__lvl__) : even for debug and for release
 DLOG(__lvl__): only for debug purpose (disable with NDEBUG macro)

Well, this will avoid slowing down the production application due to excessing
logging.

Test Plan: Nothing new

Reviewers: adrienconrath

Reviewed By: adrienconrath

Subscribers: NicolasDP

Differential Revision: http://91.121.199.76/D41