Fix Google Plugin Rate Limit Exceeded error
Fix Google Plugin Rate Limit Exceeded error

Fixes: GOOF-594

Notes:
  (tl;dr There were base retries already in place but they were failing 
  because there was no backoff. The aws gem gives us exponential backoff 
  for free)

- We are using the `google-api-client` v0.8.2 (which is quite out of
  date) to execute requests to google to obtain documents. The
  `execute!` method that is used has a default of `0` retries. The
  method then uses `Retriable.retriable` to retry IFF google returns an
  error. The `Retriable.retriable` by default has no exponential
  backoff (the :interval parameter) because there are no set retries
  passed into the `execute!` method. By passing a resonable number of
  retries the built in exponential backoff for this gem will allow us to
  bypass the `Rate Limit Exceeded` error. 

Test Plan:
- Install the Google Doc plugin
- Verify submitting a document via the plugin for an assignment
  works
- Verfiy submitting a document via the plugin for a collaboration
  works

Change-Id: Icb2a18c4fa290bead72146e92e1e1d2869ee1915
Reviewed-on: https://gerrit.instructure.com/169471
Tested-by: Jenkins
QA-Review: Pedro Fajardo <121b528f0c2f2e923ce3103793aca31b9a662ac4@instructure.com>
Reviewed-by: Joshua Orr <a2b6e8624e42637b1fd540dea491d88242856463@instructure.com>
Reviewed-by: Jeremy Slade <ea2259e2b5d53e857faf34a4f5d4862d1c54abef@instructure.com>
Reviewed-by: Bradley Horrocks <7b5c5d1f2eba6c540b8e53f17d87a9bd7dbf604b@instructure.com>
Product-Review: Jeremy Slade <ea2259e2b5d53e857faf34a4f5d4862d1c54abef@instructure.com>

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