Binding exceptions don't filter up to function logs

#### Investigative information
Timestamp: errors between 2018-08-27T22:42:22.637 and 2018-08-27T22:50:18.914
Function App name: functiondev-graphextension
Function name(s) (as appropriate): tokentest
Invocation ID:
3217a97d-637e-4693-ae1a-90be8bd35d6f
or 27475a78-c153-4f7f-bd91-90a994f07f32

Provide the steps required to reproduce the problem:

Use the latest bits with the DI work. Purposely trigger a path that would cause an exception to occur in a binding.

#### Expected behavior

The function logs print out exception details for binding exceptions encountered when trying to execute a function.

#### Actual behavior

In the functions logs (and host logs), I see just two log statements, one for the function executing and one that the execution failed.

E.g.
```

2018-08-27T22:44:49.472 [Information] Executing 'Functions.tokentest' (Reason='This function was programmatically called via the host APIs.', Id=f3fb480b-4f29-4cb5-9c98-de3faeab165f)
2018-08-27T22:44:49.480 [Error] Executed 'Functions.tokentest' (Failed, Id=f3fb480b-4f29-4cb5-9c98-de3faeab165f)
```

#### Known workarounds

I can find the exception details in the `FunctionLogs` in Kusto and in Application Insights under the `exceptions` table.

Reproduce the binding exception using the latest bits with the DI work and the tokentest function described in the issue. Compare the function and host logs with the corresponding FunctionLogs and Application Insights exceptions; done means binding exception details appear in the function logs when execution fails.

Written by the indexing model from the issue text.