JsonReader exceptions from functionswarmupsite

functionswarmupsite throwing a number of errors as mentioned below

```
Newtonsoft.Json.JsonReaderException : Error reading JObject from JsonReader. Path '', line 0, position 0.
at Newtonsoft.Json.Linq.JObject.Load(JsonReader reader,JsonLoadSettings settings)
at Newtonsoft.Json.Linq.JObject.Parse(String json,JsonLoadSettings settings)
at Newtonsoft.Json.Linq.JObject.Parse(String json)
at Microsoft.Azure.WebJobs.Script.Configuration.HostJsonFileConfigurationSource.HostJsonFileConfigurationProvider.LoadHostConfig(String configFilePath) at C:\azure-webjobs-sdk-script\src\WebJobs.Script\Config\HostJsonFileConfigurationSource.cs : 185
```

Start at src/WebJobs.Script/Config/HostJsonFileConfigurationSource.cs, especially LoadHostConfig at line 185, and trace the input reaching Newtonsoft.Json.Linq.JObject.Parse. Determine why functionswarmupsite supplies content that cannot be parsed as a JObject; done means the cause is identified and the reported JsonReaderException no longer occurs for that configuration.

Written by the indexing model from the issue text.