Disallow usage of numbers in name (first, middle and last names) and nationality fields in the people table

[santhisenan]

Post params:
firstName:123
middleName:111
lastName:A1212
gender:M
dateOfBirth:1997-09-19
nationality:1

Output:
{
"id": 5,
"first_name": "123",
"middle_name": "111",
"last_name": "A1212",
"gender": "M",
"date_of_birth": "1997-09-19",
"nationality": "1",
"updatedAt": "2018-06-04T06:02:40.440Z",
"createdAt": "2018-06-04T06:02:40.440Z"
}