Synchronize order of tox environments

The main tox configuration first ran flake8 and then the tests, while
the server's tox configuration first ran the tests and then flake8. We
harmonize both environments to first run the tests and then flake8.

Change-Id: I034536bdec9fac66b070cf851af3ba58b4f05e6f
Flake8 server/bin directory

Flake8 was not run on the server/bin directory. Hence, we now run it
and fix the current flake8 warnings.

For server/bin/eventlogging-devserver:format_config, flake8 complained
about

  F821 undefined name 'items'

. Since the function does not seem to be used at all, we remove the
whole function.

Change-Id: I4ed667dce15cff0b095fee0bdd3a91b0670f2f2e