We had capped Flake8 until flake8-import-order created a new release. We
can now add a lower bound to flake8-import-order and uncap Flake8.

Fix project config file discovery

*Description of changes*

Keep searching past the current directory to find project config files.

*Related to:*  #181

See merge request !91

Flake8 3.0 was stopping once it found the current directory but the
historical behaviour (that we didn't intend to break) searched past
that (towards root) until it found one of the project/local config
file names that could be read.

Closes #181

This allows for other text after `# noqa`.

Related to #180

Handle repeated --quiet options again

*Description of changes*

Handle `-q`/`--quiet` again.

*Related to:*  #180

See merge request !89

Fundamentally on Flake8 2.x using -q altered the format of the errors
(and the behaviour a little) so it makes the most sense to implement
this logic with formatters rather than messy logic spread throughout
the project.

The FilenameOnly formatter will keep track of filenames already reported
and only print the name once while Nothing will print nothing.

Closes #180

Wire-up --statistics again

*Description of changes*

Make `--statistics` work again

*Related to:*  #180

See merge request !87

Set-up and stop our formatter

*Description of changes*

Make `--output-file` work consistently (especially without verbose logging)

*Related to:*  #180

See merge request !86