.retry: add predicate option, which could be used to decide which errors should trigger a retry

[adrian-gierakowski]

similar to what's available in bluebird-retry

example usage:

Aigle.retry(
  { predicate: error => error.statesCode === 429 },
  () => requestPromise.get(someUrl)
)

or

Aigle.retry(
  { predicate: MyErrorClass },
  myFunction
)

[suguru03]

@adrian-gierakowski Thanks for the idea!
It looks really useful.
I could support a similar syntax as assert.throws or assert.rejects as well. ✍️
https://nodejs.org/api/assert.html#assert_assert_throws_fn_error_message

[adrian-gierakowski]

@suguru03 nice idea with using assert interface. I might work on this tomorrow.