Implement retry policy for some API calls

[ponkin]

Some dropbox API calls may be rate-limited in certain conditions by responding with HTTP '429 Too Many Requests' (with header 'Retry-After: 1') May be we can set up some 'retry policy', to automatically handle such situation, for example: const dbx = new Dropbox({ accessToken: token, numberOfRetries: 10 });

default will be 0.

[greg-db]

Thanks for writing this up! I can't make any promises, but I'll send this request along to the team.