Updates

Updated all commands to new style. See command.md
Added new command pxc node describe
Added support for both pxc in kubectl plugin and as a standalone program. You can now set the endpoint to directly communicate with the Portworx node, instead of tunneling through the Kubernetes API server
Created new simple library for components. See the following examples:
- In pxc/example-component
- Repo: https://github.com/portworx/pxc-component-example
Cleaned up global flags in the help screen

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