Merge branch 'pulses' of github.com:metabase/metabase into pulses

...tend/src/admin/databases/components/DatabaseEditForms.jsx

frontend/src/admin/databases/databases.controllers.js

frontend/src/setup/components/DatabaseStep.jsx

frontend/src/setup/reducers.js

resources/migrations/020_add_pulse_tables.yaml

src/metabase/api/database.clj

src/metabase/api/pulse.clj

src/metabase/api/routes.clj

src/metabase/core.clj

src/metabase/db.clj

src/metabase/models/pulse_channel.clj

src/metabase/models/setting.clj

src/metabase/task/send_pulses.clj

test/metabase/api/database_test.clj