Jclouds property format

- Add ControlledDynamicWebAppCluster.CONTROLLER_SPEC

- jclouds config properties: accept camel case or hyphen format. Previously, only accepted hyphenated format such as `brooklyn.jclouds.aws-ec2.private-key-file`; now also accepts `brooklyn.jclouds.aws-ec2.privateKeyFile`. TODO: we should decide which one format we want to encourage/support, and deprecate the other. I prefer the camel case because that matches what's used everywhere else in brooklyn.

- PortMapping: null checking. After seeing a null logged in the exception message, adds a null-check earlier.