Add node name option to Chef knife converge tasks

Allows the optional "node name" parameter to be passed to the knife converge command. This give entities control over the name, so that the node's details can be retrieved from Chef server later if required.
Add feed to publish Chef attributes to sensors

Adds ChefAttributeFeed class
ChefAttributeFeed builder + sensor naming

Switch to use a Builder for ChefAttributeFeed - allows polling period to be user defined, and also now supports adding sensors with arbitrary names.
ChefAttributeFeed - respond to review comments

See pull request 953 [https://github.com/brooklyncentral/brooklyn/pull/953]
Merge pull request #953 from richardcloudsoft/chef-enhancements

Extra Chef features - set node name, and expose Chef attributes as Brooklyn sensors