* Move tracing exporter registration
This doesn't belong in the library and should be configured by the
consumer of the opencensus package.
* Rename `vkublet` package to `node`
`vkubelet` does not convey any information to the consumers of the
package.
Really it would be nice to move this package to the root of the repo,
but then you wind up with... interesting... import semantics due to the
repo name... and after thinking about it some, a subpackage is really
not so bad as long as it has a name that convey's some information.
`node` was chosen since this package deals with all the semantics of
operating a node in Kubernetes.
This makes the concept of a `Provider` wholely implemented in the cli
implementation in cmd/virtual-kubelet.
It allows us to slim down the interfaces used in vkubelet (and
vkubelet/api) to what is actually used there rather than a huge
interface that is only there to serve the CLI's needs.
