##### SUMMARY
get_vm() method vmware.py module utility fails with KeyError if uuid is not in the module param from whch method is invoked

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
vmware.py module util

##### ANSIBLE VERSION
```
ansible 2.9.0.dev0
```

##### OS / ENVIRONMENT
Ubuntu 16

##### STEPS TO REPRODUCE
Creating new module. 'uuid' is not in my module arguments. 
Called get_vm() 

pyv = PyVmomi(module=module)
vm = pyv.get_vm()

##### EXPECTED RESULTS
Call should return vm_id if it exists

##### ACTUAL RESULTS
```
Get error
An exception occurred during task execution. To see the full traceback, use -vvv. The error was: KeyError: 'uuid'
fatal: [localhost]: FAILED! => {"changed": false, "module_stderr": "Traceback (most recent call last):\n  File
\"/home/vmware/.ansible/tmp/ansible-tmp-1565095783.75439-259726275713856/AnsiballZ_vmware_content_deploy_template.py\", line 125, in <module>\n    _ansiballz_main()\n  File \"/home/vmware/.ansible/tmp/ansible-tmp-1565095783.75439-259726275713856/AnsiballZ_vmware_content_deploy_template.py\", line 117, in _ansiballz_main\n    invoke_module(zipped_mod, temp_path, ANSIBALLZ_PARAMS)\n  File \"/home/vmware/.ansible/tmp/ansible-tmp-1565095783.75439-259726275713856/AnsiballZ_vmware_content_deploy_template.py\", line 51, in invoke_module\n    spec.loader.exec_module(module)\n  File \"<frozen importlib._bootstrap_external>\", line 665, in exec_module\n  File \"<frozen importlib._bootstrap>\", line 222, in _call_with_frames_removed\n  File \"/tmp/ansible_vmware_content_deploy_template_payload_69cftg21/__main__.py\", line 271, in <module>\n  File \"/tmp/ansible_vmware_content_deploy_template_payload_69cftg21/__main__.py\", line 241, in main\n  File \"/tmp/ansible_vmware_content_deploy_template_payload_69cftg21/ansible_vmware_content_deploy_template_payload.zip/ansible/module_utils/vmware.py\", line 891,
in get_vm\nKeyError: 'uuid'\n", "module_stdout": "", "msg": "MODULE FAILURE\nSee stdout/stderr for the exact error", "rc": 1}

```

port=dict(type='int',
                  default=443,
                  fallback=(env_fallback, ['VMWARE_PORT'])),
        validate_certs=dict(type='bool',
                            required=False,
                            default=True,
                            fallback=(env_fallback, ['VMWARE_VALIDATE_CERTS'])
                            ),
        proxy_host=dict(type='str',
                        required=False,
                        default=None,
                        fallback=(env_fallback, ['VMWARE_PROXY_HOST'])),
        proxy_port=dict(type='int',
                        required=False,
                        default=None,
                        fallback=(env_fallback, ['VMWARE_PROXY_PORT'])),
    )
def connect_to_api(module, disconnect_atexit=True, return_si=False):
    hostname = module.params['hostname']
    username = module.params['username']
    password = module.params['password']
    port = module.params.get('port', 443)
    validate_certs = module.params['validate_certs']
    if not hostname:
        module.fail_json(msg="Hostname parameter is missing."
                             " Please specify this parameter in task or"
                             " export environment variable like 'export VMWARE_HOST=ESXI_HOSTNAME'")
    if not username:
        module.fail_json(msg="Username parameter is missing."
                             " Please specify this parameter in task or"