Correctly handle HTTP errors in RequestLogPolicy

[pharaujo]

The condition that tests the HTTP status code to decide whether or not to upgrade log severity never sees the 4xx and 5xx responses because they are encapsulated in a StorageError.

Addresses #214

[ghost]

All CLA requirements met.

[pharaujo]

Hey @mohsha-msft the build failure doesn't seem related to my change, as both master and dev branches seem to be crashing in the same way when I run the test locally.

How should I proceed?

[mohsha-msft]

@pharaujo

We appreciate your efforts to improve Azure Blob Go SDK!

The build pipeline uses private credentials (storage account name and account key) which we do not expose to public PRs. Please raise the review request anyway. We'll take a look at the PR and will run the tests after that using our credentials.

For more clarification, reach out to us.

[pharaujo]

@mohsha-msft

(...) Please raise the review request anyway. We'll take a look at the PR and will run the tests after that using our credentials.

This already is the PR with the logging fix. Do you need anything else from my end?

[mohsha-msft]

Merging the branch with issue/http-log-policy branch to run regression tests. Raised a separate PR to merge issue/http-log-policy with dev #228