Merge pull request #13 from zepag/master

Added a bit of info on how to launch webtests and perf tests.
fork is the default
Directly get a java.lang.Long (easier to understand for non-scala devs)

See
http://stackoverflow.com/questions/15544635/gatling-gives-error-when-usi
ng-parameter-for-ramp
Merge pull request #14 from slandelle/master

Just a few tweaks, Thanks to @slandelle