Stargirl Flowers

So `verify`/`validate_certificate` is not a usual parameter to urllib3's `urlopen` method. Looking at requests it seems it [modifies the actual connection](https://github.com/requests/requests/blob/master/requests/adapters.py#L201) it gets from the pool to do verification. It...

@sigmavirus24 that seems pretty reasonable.

I'm fine with having the AppEngineManager do timeout retries, however, I want to be cautious because of the overall 60s request deadline on App Engine.

> conscious/cautious of the 60s request deadline? I'm not sure what that would look like. Either way, the application will always receive a top-level `DeadlineExceeded` exception whenever the request timer...

There are ~~two~~three major issues with that: 1. App Engine's request timer may start before application code is called. 2. There's no way to know how many seconds are left...

App engine is basically a bunch of deadlines! :D There's a top-level request deadline as well as deadlines for every RPC (datastore calls, memcache calls, and of course, URLFetch calls)....

I added some basic tests for this and it's looking great. I still want to test this with real hardware. :)

`sphinx-docstring-typing` seems to take a different approach than you guys are wanting here. Some context - I wrote it for the new [google-auth-library-python](https://github.com/GoogleCloudPlatform/google-auth-library-python). I wanted us to be able to...

> We'll need a Session-like class in front of PoolManager that is more implicit. I like this but I don't have a strong need. Personally, I would just like a...

> Maybe feature a kind of registry that external plugins can provide additional services for. Sounds reasonable.