Externalize Gatling status codes
Clean up Http request/response
Fix build
Introduce response processor, close #1033
Reorganize/clean up gatling.conf, close #1055
Fix messages
Expose predefined HTPP header values
Have feeder and request bodies support absolute paths
Improve and expose CSV parsing
Add "application/x-www-form-urlencoded" constant
Minor clean up
Add RequestBodyProcessors predefs
Upgrade timestamped AHC 1.7.13, close #1072