<!--- Verify first that your feature was not already discussed on GitHub -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
The `ssh_opts` parameter relies on setting environment variables for git, such as GIT_SSH. Git did not recognize this environment variable until version 2.3.0 (see https://git-scm.com/docs/git/2.3.0), and many contemporary OSes (RHEL 7, CentOS7) include older versions of Git (1.8.3.1).

It would be useful to provide a warning in this case, similar to the warning for the `depth` parameter. E.g. "Your git version is too old to support the ssh_opts argument."

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
git.py
source control, git module

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
It would save users time when trying to troubleshoot failed git connections via SSH.

<!--- Paste example playbooks or commands between quotes below -->
```yaml
- name: clone a git repo
  git:
    repo: git@github.com:cherdt/hello_ansible.git
    dest: /opt/hello_ansible
    version: master
    ssh_opts: "{{-o IdentityFile=github_id_rsa}}"
```

<!--- HINT: You can also paste gist.github.com links for larger files -->

submodules_updated = False
    if recursive and not bare:
        submodules_updated = submodules_fetch(git_path, module, remote, track_submodules, dest)
        if submodules_updated:
            result.update(submodules_changed=submodules_updated)
            if module.check_mode:
                result.update(changed=True, after=remote_head)
                module.exit_json(**result)
            
            submodule_update(git_path, module, dest, track_submodules, force=force)
    
    result['after'] = get_version(module, git_path, dest)
    if result['before'] != result['after'] or local_mods or submodules_updated or remote_url_changed:
        result.update(changed=True)
        if module._diff:
            diff = get_diff(module, git_path, dest, repo, remote, depth, bare, result['before'], result['after'])
            if diff:
                result['diff'] = diff
    if archive:
        
        
        if module.check_mode:
            result.update(changed=True)
            module.exit_json(**result)
        create_archive(git_path, module, dest, archive, archive_prefix, version, repo, result)
    module.exit_json(**result)
if __name__ == '__main__':
    main()