fix: ssl socket leak

[alexpenev-s]

-closes:#32

[mention-bot]

By analyzing the blame information on this pull request, we identified @fengmk2, @lattmann and @pmalouin to be potential reviewers

[fengmk2]

https://github.com/node-modules/agentkeepalive/pull/33/files#diff-5f7fb0850412c6be189faeddea6c5359R226 createSocket() will do the _extend logic.

[alexpenev-s]

It extends its own copy of options.
On a subsequent request, when addRequest()is called. It is called with the options specified by https.request(options) which don't have the ca property.

The issue occurs when ca is in the global options object and not in the options coming from the request.

[fengmk2]

@saperal Can you add a test case for this change?

And you can also send a pr for nodejs itself too. https://github.com/nodejs/node/blob/master/lib/_http_agent.js#L108

[fengmk2]

@saperal nice move! I will merge this soon. https://github.com/nodejs/node/pull/5713/files

[fengmk2]

Landed 88d1e1e

[fengmk2]

2.1.1