Swagger spec compatibility features

Added few compatibility fixes:

- Allow setting `header` data type. This comes useful when your API requires i.e. authtoken to be passed in the request header. Usage:

```
validation: {
    token: { isRequired: true, type: 'string', scope: 'header' }
},
```

- Add support for arrays of models. This is especially useful if you POST or PUT complex data types:

```
validation: {
    books: { isRequired: true, type: 'array', swaggerType: 'Book', scope: 'body' }
},
models: {
    Book: {
        id: 'Boook',
        properties: {
            name: { type: 'string' },
            code: { type: 'integer' }
        }
    }
}
``` 
then your POST/PUT payloads can look like this:
```
{
    "books": [{ "name": "The Hobbit", "code": 1 }, { "name": "Lord of The Rings", "code": 2 }]
}
```

- do not create duplicate swagger entries for the same routes. 
Example:
```
{ url: '/users', version: '1.0.0' }
{ url: '/users', version: '1.2.3' }
```
should not create 2 entries in swagger