Bring build triggering back to life
Prevent stat with lower bound of 0 from causing histogram exception
Merge branch 'master' of https://github.com/excilys/gatling

# By Ivan Mushketyk (3) and others
# Via Pierre DAL-PRA (1) and Stephane Landelle (1)
* 'master' of https://github.com/excilys/gatling:
  Bring build triggering back to life
  minor clean up
  Added checkbox in recorder to configure removing conditional cache headers
  Added configuration key to leave/remove conditional cache headers
  Filtering conditional headers in recorder