Fix an argument of launching a slave
Update EC2Cloud.java

Cherry-pick from https://github.com/eucacolby/ec2-plugin/commit/47eef794f1a31407ceb333cd87a4105ee5fdaf33
Merge pull request #74 from okigan/master

Update EC2Cloud.java -- fixes race condition that prevents proper function when 2 or more clouds configured
Merge pull request #73 from ikikko/fix_argument_of_launching_slave

Fix an argument of launching a slave