<!--- 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 -->

module.fail_json(msg="Could not determine remote revision for %s" % version, stdout=out, stderr=err, rc=rc)
    out = to_native(out)
    if tag:
        
        for tag in out.split('\n'):
            if tag.endswith(version + '^{}'):
                out = tag
                break
            elif tag.endswith(version):
                out = tag
    rev = out.split()[0]
    return rev
def is_remote_tag(git_path, module, dest, remote, version):
    cmd = '%s ls-remote %s -t refs/tags/%s' % (git_path, remote, version)
    (rc, out, err) = module.run_command(cmd, check_rc=True, cwd=dest)
    if to_native(version, errors='surrogate_or_strict') in out:
        return True
    else:
        return False
def get_branches(git_path, module, dest):
    branches = []
    cmd = '%s branch --no-color -a' % (git_path,)
    (rc, out, err) = module.run_command(cmd, cwd=dest)
    if rc != 0:
        module.fail_json(msg="Could not determine branch data - received %s" % out, stdout=out, stderr=err)
    for line in out.split('\n'):
        if line.strip():
            branches.append(line.strip())
    return branches
def get_annotated_tags(git_path, module, dest):