Fix handling of logical lines with noqa

When attempting to centralize all inline NoQA handling in the StyleGuide
we inadvertently broke plugins relying on it in combination with checker
state. For example, the check for E402 relies both on NoQA and the state
to determine if it has seen a non-import line. Placing NoQA on the sole
line that is not an import is more elegant than placing it on each of
the following import lines.

Closes #186