Add apikey management API

database/bindata.go

database/migrations/0003_add_user_apikey.up.sql

models/apikey.go

models/apikey_db.go

models/db_helpers.go

restapi/configure_rednerd.go

restapi/embedded_spec.go

restapi/handlers/user-apikey-add.go

restapi/handlers/user-apikey-delete.go

restapi/handlers/user-apikey-list.go

restapi/operations/logging.go

restapi/operations/prometheus.go

restapi/operations/rednerd_api.go

restapi/operations/user_management/user_apikey_add.go

.../operations/user_management/user_apikey_add_parameters.go

.../operations/user_management/user_apikey_add_prometheus.go

...i/operations/user_management/user_apikey_add_responses.go

.../operations/user_management/user_apikey_add_urlbuilder.go

restapi/operations/user_management/user_apikey_delete.go

...erations/user_management/user_apikey_delete_parameters.go