Standardize on 'vhost' in logging

[johanrhodin]

Proposed Changes

Almost all logging of vhost is either virtual host or vhost. Grepping I only found one VHost logged. This PR switches that to vhost and fixes a typo.

Types of Changes

What types of changes does your code introduce to this project?

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)
• Build system and/or CI

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)

[michaelklishin]

@johanrhodin perhaps a company that has bootstrapped itself off of years of RabbitMQ R&D and directly makes money off of RabbitMQ could contribute more than typo fixes. If typo fixes is all you've got then just don't bother.