Don't cache the gravity response in /auctions
Don't cache the gravity response in /auctions

Slack
context: https://artsy.slack.com/archives/C02BC3HEJ/p1550251913148600

In brief:

- Recently turned on Rate limiting in force
- Previously, caching at /auctions endpoint was broken
- Enabling rate limiting fixed this cache
  + but we don't want to cache auctions response, so remove `cache`
    option in `auctions.fetch`

Some evidence of (undesired) caching going into effect:

- Data Dog trace showing queries to Gravity:
https://app.datadoghq.com/apm/trace/1497793948768870733
  + Note how all traces _in the future_ of this trace respond very quickly,
  and don't integrate with Force's HTTP service or Gravity.

anandaroop/force,oxaudo/force,artsy/force,eessex/force,oxaudo/force,damassi/force,eessex/force,izakp/force,cavvia/force-1,oxaudo/force,oxaudo/force,anandaroop/force,izakp/force,izakp/force,damassi/force,erikdstock/force,erikdstock/force,mzikherman/force,eessex/force,mzikherman/force,xtina-starr/force,yuki24/force,yuki24/force,cavvia/force-1,cavvia/force-1,xtina-starr/force,joeyAghion/force,izakp/force,joeyAghion/force,cavvia/force-1,xtina-starr/force,mzikherman/force,yuki24/force,eessex/force,joeyAghion/force,artsy/force-public,artsy/force-public,anandaroop/force,artsy/force,anandaroop/force,xtina-starr/force,erikdstock/force,mzikherman/force,yuki24/force,erikdstock/force,damassi/force,artsy/force,damassi/force,artsy/force,joeyAghion/force