##### 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}

```

"""
        Get all host system managed object
        Args:
            cluster_name: Name of Cluster
            esxi_host_name: Name of ESXi server
        Returns: A list of all host system managed objects, else empty list
        """
        host_obj_list = []
        if not self.is_vcenter():
            hosts = get_all_objs(self.content, [vim.HostSystem]).keys()
            if hosts:
                host_obj_list.append(list(hosts)[0])
        else:
            if cluster_name:
                cluster_obj = self.find_cluster_by_name(cluster_name=cluster_name)
                if cluster_obj:
                    host_obj_list = [host for host in cluster_obj.host]
                else:
                    self.module.fail_json(changed=False, msg="Cluster '%s' not found" % cluster_name)
            elif esxi_host_name:
                if isinstance(esxi_host_name, str):
                    esxi_host_name = [esxi_host_name]
                for host in esxi_host_name:
                    esxi_host_obj = self.find_hostsystem_by_name(host_name=host)
                    if esxi_host_obj:
                        host_obj_list.append(esxi_host_obj)
                    else:
                        self.module.fail_json(changed=False, msg="ESXi '%s' not found" % host)
        return host_obj_list
    def host_version_at_least(self, version=None, vm_obj=None, host_name=None):