Activate pep8 check that _ is imported

Remove the specification in tox.ini that _ is a builtin so that
it will no longer assume that _ does not need to be imported.

This helps ensure that the _ from i18n is used.

Activating this check did not flag any violations.

Change-Id: I077b9b2060e618823ef6dd6f95ce9fe7dcc52a06
Fix tiny typo in server.py

Missing the word 'to'

Change-Id: I6d1cc923b4085f0451a3a4b2d4b716b2c7ac5e96
Updated from global requirements

Change-Id: I6c7256a412154915603bea4541383bf6fe3bfc5c
Merge "Activate pep8 check that _ is imported"
Merge "Updated from global requirements"