Nodes authentication and katello environment support

Summary:
- nodes: using oauth instead of node SSL certificate for pulp REST API.
- platform: enabled oauth by default with generated key and secret.
- nodes: pass node cert still used for downloading in agent request instead of including in bind payloads.
- add consumer_id() to agent Conduit.  Already implemented in subclass.
- nodes: add profiler to inject parent node settings instead of relying on consumer.cert with wont be there in the katello environment:
  - host
  - port
  - node_certificate
- update nodes distributor (and .conf) to no longer include certificate.
- update node handler to pass *parent_settings* passed in *options* when fetching the bindings from the parent.
- handler/model simplified while refitting to use the *resources* module to support passed credentials instead of reading the consumer.cert.  Since all CRUD methods on model objects must always be performed using the pulp binding for the local (child) node the extra hierarchy, multiple inheritance and slightly wonky naming was just cruft.
- documentation updates regarding node.conf and oauth authentication.
- updated unit tests for all this crap.
- noticed that the remote manifest methods were not checking the download result and raising an exception so fixed that.
- noticed that, at some point, the nectar error report became an object and so including it instead of report.error_msg in the raised exception was causing serialization exceptions.
- updated CN in the node certificate to be the node hostname instead of embedding user_id:password:pid since it's not longer used to REST auth.
- updated node cert gen script to use the cert location in the nodes.conf instead of hard coded.  Also changed CN.