Remove unremovable default hackney pool

[izelnakri]

This was needed, because my tests were failing due to this new default hackney pool usage that was not removable from outside. #81

NOTE: we should cut a MINOR release afterwards as this is a breaking change.

[ayrat555]

@izelnakri Can you please give some instructions for reproducing your error?

[izelnakri]

@ayrat555 sure, the link I provided above explains it: #81

The code diff between those links is the reason why I had to disable a pool for my use case. When my eth library test case starts it makes thousands of http requests that go to a pool and they get stuck, even when the testrpc server goes live, making the tests unable to run/hang since they wait for a successful rpc response.

Also I had to do thousands of requests, couldnt figure out a better way to test eth library since it depends on an external testrpc node.js cli/process, and couldnt figure it out if elixir Ports could be usable after hours/days of investigation back then.

[InoMurko]

@izelnakri the checkout_timeout comes from your pool being exhausted. which comes from a hackney bug I reported months ago:
benoitc/hackney#643

Are you sure this two things are not releated?

[izelnakri]

@izelnakri the checkout_timeout comes from your pool being exhausted. which comes from a hackney bug I reported months ago:
benoitc/hackney#643

Are you sure this two things are not releated?

👍 most likely they are related, checking it now. Also we should provide this option to adjust the pool, make the library as flexible as possible so I think this MR should be merged regardless 😉

[InoMurko]

Absolutely.

Please force hackney from the tip of master and try out your test.

[izelnakri]

@InoMurko yes It worked. Lets merge this PR and then update httpoison to 1.7.0, not sure if this would fix the hackney issue but we'll see I guess ;)