Lavaclient

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* Fix SSH methods bug in which ambari node is targeted

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* General
* Add ambari credential management methods
* Re-enabled stacks create/delete

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* General
* Add ssh_tunnel method/command to help set up SSH tunnels to a cluster
* Add additional debugging levels
* Get V2 API endpoints from service catalog

* CLI
* Improve display for node components
* Add confirmations for delete methods, e.g. `clusters delete`
* Piping output to another command disables pretty printing so that it is
easier to parse

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* Fix cluster create bug in CLI in which missing credentials are not detected
properly
* Update dependencies for keystoneclient and oslo.i18n to avoid library
conflict issue

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* Client
* Let `node_groups` argument be a nested dict, in addition to the original
list of dicts format
* CLI
* Add prompt to `cluster create` to confirm whether ssh credential should
automatically be created from `$HOME/.ssh/id_rsa.pub`

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* Initial release