Function cannot write to $web container

#### Investigative information

Please provide the following:

- Timestamp: 13:41 AWST, 13/12/2018
- Function App version (1.0 or 2.0): 2.0.12210.0
- Invocation ID: 42aebb5b-0ac4-44e4-b383-d68f59f4c555
- Region: Australia Southeast

#### Repro steps

Provide the steps required to reproduce the problem:

1. Create a Function 2.0
2. Create a GPv2 storage account
3. Setup a static website within the GPv2 storage
4. Attempt to use the Azure Blob Storage output method within the function to the new $web container

*Alternatively set function to be triggered by $web, function will not run at all and no errors appear.*

#### Expected behavior

Provide a description of the expected behavior.

Function should output a blob to the $web container with no issues.

#### Actual behavior

Function throws error message:

```
*** [Error] Executed 'Functions.****' (Failed, Id=***)
Validation failed for property 'BlobPath', value '$web/index.html'. The field BlobPath is invalid.
```

#### Known workarounds

Use the Node.js preview library and upload the blob within the function itself.

#### Related information

Provide any related information

* Programming language used: Javascript
* Screenshot of config

The payload names no repository files or tests; start by reproducing the Azure Functions 2.0 steps with a GPv2 storage account and the $web container. Compare Blob Storage output and $web-trigger behavior with the reported BlobPath validation error; done means the function can write to and trigger from $web without errors.

Written by the indexing model from the issue text.