Update dcos_generate_config.sh --help to display the right help messages
Update dcos_generate_config.sh --help to display the right help messages

```
usage: dcos_installer [-h] [--hash-password [password]]
                      [--set-superuser-password [password]] [-v] [--offline]
                      [--cli-telemetry-disabled] [--web] [--version]
                      [--aws-cloudformation] [--genconf] [--validate-config]
                      [--preflight] [--postflight] [--install-prereqs]
                      [--uninstall] [--deploy]

DC/OS Install and Configuration Utility

optional arguments:
  -h, --help            show this help message and exit
  --hash-password [password]
                        Hash a password and print the results to copy into a
                        config.yaml.
  --set-superuser-password [password]
                        Hash the given password and store it as the superuser
                        password in config.yaml
  -v, --verbose         Verbose log output (DEBUG).
  --offline             Do not install preflight prerequisites on CentOS7,
                        RHEL7 in web mode
  --cli-telemetry-disabled
                        Disable the CLI telemetry gathering for SegmentIO
  --web                 Run the web interface
  --version             Print the DC/OS version
  --aws-cloudformation  Generate AWS Advanced AWS CloudFormation templates
                        using the provided config
  --genconf             Execute the configuration generation (genconf).
  --validate-config     Validate the configuration for executing --genconf and
                        deploy arguments in config.yaml
  --preflight           Execute the preflight checks on a series of nodes.
  --postflight          Execute postflight checks on a series of nodes.
  --install-prereqs     Execute the preflight checks on a series of nodes.
  --uninstall           Execute uninstall on target hosts.
  --deploy              Execute a deploy.
```

BenWhitehead/dcos,asridharan/dcos,dcos/dcos,xinxian0458/dcos,asridharan/dcos,lingmann/dcos,kensipe/dcos,BenWhitehead/dcos,jeid64/dcos,GoelDeepak/dcos,mesosphere-mergebot/dcos,surdy/dcos,darkonie/dcos,mellenburg/dcos,mesosphere-mergebot/dcos,GoelDeepak/dcos,mesosphere-mergebot/dcos,kensipe/dcos,jeid64/dcos,kensipe/dcos,mesosphere-mergebot/dcos,xinxian0458/dcos,mellenburg/dcos,mnaboka/dcos,vishnu2kmohan/dcos,vishnu2kmohan/dcos,branden/dcos,GoelDeepak/dcos,BenWhitehead/dcos,dcos/dcos,jeid64/dcos,amitaekbote/dcos,surdy/dcos,dcos/dcos,surdy/dcos,mellenburg/dcos,amitaekbote/dcos,mesosphere-mergebot/mergebot-test-dcos,amitaekbote/dcos,darkonie/dcos,branden/dcos,amitaekbote/dcos,vishnu2kmohan/dcos,xinxian0458/dcos,lingmann/dcos,mesosphere-mergebot/mergebot-test-dcos,mnaboka/dcos,darkonie/dcos,jeid64/dcos,darkonie/dcos,vishnu2kmohan/dcos,lingmann/dcos,darkonie/dcos,mellenburg/dcos,dcos/dcos,mnaboka/dcos,branden/dcos,branden/dcos,mnaboka/dcos,mesosphere-mergebot/mergebot-test-dcos,lingmann/dcos,mnaboka/dcos,BenWhitehead/dcos,surdy/dcos,kensipe/dcos,xinxian0458/dcos,asridharan/dcos,GoelDeepak/dcos,mesosphere-mergebot/mergebot-test-dcos,dcos/dcos,asridharan/dcos