Azure function proxy does not startup when response body contains a quote "

*Problem:*
Azure Function Proxy response.body does not support quotes.

When i have the proxy configured like example 1.
Then i call http://my-function.azurewebsites.net/Helloworld i get:
`Hello World.`

When i add a quote to the response body like example 2.
Function host is not running.

Example 1 without quote
```
{
"$schema": "http://json.schemastore.org/proxies",
"proxies": {
"Helloworld": {
"matchCondition": {
"route": "Helloworld",
"methods": [
"POST"
]
},
"responseOverrides": {
"response.statusCode": "200",
"response.statusReason": "OK",
"response.headers.Content-Type": "application/xml",
"response.body": "Hello World."
}
}
}
}
```

Example 2 with quote

```
{
"$schema": "http://json.schemastore.org/proxies",
"proxies": {
"Helloworld": {
"matchCondition": {
"route": "Helloworld",
"methods": [
"POST"
]
},
"responseOverrides": {
"response.statusCode": "200",
"response.statusReason": "OK",
"response.headers.Content-Type": "application/xml",
"response.body": "Hello World \"."
}
}
}
}
```