Use consistent command line help summary for all Navigator CLI tools

[wallrj]

Fixes: #341

Release note:

NONE

[wallrj]

Here's how it looks:

find . -maxdepth 1 -executable -type f  | while read f; do echo; echo "\$ $f --help"; $f --help | head -n 8; done

$ ./navigator-controller_linux_amd64 --help

Launch a Navigator controller.

Navigator is a Kubernetes extension for managing common stateful services on Kubernetes.
Documentation is available at https://navigator-dbaas.readthedocs.io.

Usage:
  navigator-controller [flags]

$ ./navigator-apiserver_linux_amd64 --help

Launch a Navigator API server.

Navigator is a Kubernetes extension for managing common stateful services on Kubernetes.
Documentation is available at https://navigator-dbaas.readthedocs.io.

Usage:
  navigator-apiserver [flags]

$ ./navigator-pilot-elasticsearch_linux_amd64 --help

Launch a Navigator Elasticsearch Pilot.

Navigator is a Kubernetes extension for managing common stateful services on Kubernetes.
Documentation is available at https://navigator-dbaas.readthedocs.io.

Usage:
  navigator-pilot-elasticsearch [flags]

$ ./navigator-pilot-cassandra_linux_amd64 --help

Launch a Navigator Cassandra Pilot.

Navigator is a Kubernetes extension for managing common stateful services on Kubernetes.
Documentation is available at https://navigator-dbaas.readthedocs.io.

Usage:
  navigator-pilot-cassandra [flags]

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This pull-request has been approved by: kragniz

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