Add support for rejectUnauthorized flag

[foch]

Purpose of this PR is to add the possibility to target in HTTPS a server with an "invalid" certificate, i.e. not recognized by a well-known authority, but for instance self-signed. This is useful in a corporate environment, where our SharePoint (using NTLM) has a certificate signed by the company root certificate.

It's the equivalent of the --insecure flag of curl, hence the name of the new flag, secure. Of course, I left secure as default!

It will provide a solution for issue #64

[phgnx]

I need this fix aswell

[SamDecrock]

Cant you just pass in "rejectUnauthorized" using the regular options object:

httpntlm.get({
    url: "https://someurl.com",
    username: 'm$',
    password: 'stinks',
    workstation: 'choose.something',
    domain: '',
    rejectUnauthorized: true
}, function (err, res){
    if(err) return err;

    console.log(res.headers);
    console.log(res.body);
});

[traveling-developer]

For me setting the "rejectUnauthorized" flag to false helped:

httpntlm.get({
    url: "https://someurl.com",
    username: 'm$',
    password: 'stinks',
    workstation: 'choose.something',
    domain: '',
    rejectUnauthorized: false
}, function (err, res){
    if(err) return err;

    console.log(res.headers);
    console.log(res.body);
});

[SamDecrock]

Closing PR without merging passing the rejectUnauthorized headers just works.