Add max-complexity to pep8 for Horizon

Picked this up from Keystone. It sounds like a good defense to have from
further making our code more complex.

The current highest complexity is 32, set the maximum complexity
for flake8 to 33. This should help to keep code simple and
maintainable. It should be possible to reduce the maximum
complexity to something closer to 20 with relatively small efforts.

openstack_dashboard.dashboards.identity.projects.workflows:
    'UpdateProject.handle' is complexity of 32
openstack_dashboard.dashboards.project.access_and_security.security_groups.forms:
    'AddRule.clean' is complexity of 20
openstack_dashboard.dashboards.project.instances.workflows.create_instance:
    'SetInstanceDetailsAction.clean' is complexity of 26
horizon.exceptions:
    'handle' is complexity of 24

Change-Id: I58cc20972aac221012f248e8135151b1243dae35
Dropdown Actions For Database Details Page

adds dropdown actions to the database/trove details page. this was
missed in Ic09385d19b417b256cbc51d044d66ecbb54c7d52, aka
blueprint detail-pages-ia .

Change-Id: I3c30b5ec9e22f0ac709d147443cae02b359d7c36
Closes-Bug: #1382918
Merge "Add max-complexity to pep8 for Horizon"
Merge "Dropdown Actions For Database Details Page"