Honor NPM's cafile configuration

[mschnee]

If you are behind a corporate firewall with a self-signed certificate, the correct way to configure node and npm is to use npm config set cafile="/path/to/cert.pem"

This PR honors this configuration being passed to the request library in the same manner that node-gyp does (using the same readCAFile function, to boot)

[max-mapper]

nice, two questions:

• could you change it to be fs.readFile instead of readFileSync?
• is this easy to add a test for? just to catch regressions in the future in case we break it. if it's not easy then no worries

[mschnee]

I'll look into readFileSync ->readFile with a clean head in the morning: I was essentially copying some of node-gyp's code over as-is. Apologies for taking the lazy approach ;)

As for the test: yes, it can be tested by setting up a small local server and ensuring both sides behave. Again, node-gyp to the rescue (https://github.com/nodejs/node-gyp/commit/8c4b0ffa503aa385f4186e028542dcedca2efeee)

I will create the test.

[sla89]

@maxogden Any chance that this will be merged as is when the conflicts get solved? We really need this.

[mschnee]

Closing as abandoned :(