Creating test user service; Add fraud prevention headers

[DarkSide666]

Features:

• Adds service for creating test users
• Adds fraud prevention headers
• Adds ability to set default headers for all requests (trough Request object or Environment)
• Adds connection method header values

Fixes:

• OAuth should use RequestURL constants too

Usage example:

use HMRC\Environment\Environment;
use HMRC\Request\RequestHeader;
use HMRC\Request\RequestHeaderValue;

Environment::getInstance()->setDefaultRequestHeaders([
    RequestHeader::GOV_CLIENT_CONNECTION_METHOD => RequestHeaderValue::WEB_APP_VIA_SERVER,
    RequestHeader::GOV_CLIENT_PUBLIC_IP => $_SERVER['REMOTE_ADDR'],
    RequestHeader::GOV_CLIENT_PUBLIC_PORT => $_SERVER['REMOTE_PORT'],
    RequestHeader::GOV_CLIENT_USER_AGENT => $_SERVER['HTTP_USER_AGENT'],
    RequestHeader::GOV_CLIENT_USER_IDS => 'user='.$this->user->id,
    RequestHeader::GOV_VENDOR_VERSION => 'app='.$this->app->version,
]);

[s-patompong]

Sorry I was busy and just see this today. I'll need to have a look at the code and will merge if everything is ok.

[DarkSide666]

No problem. I will use this PR in production after release which will happen this Sunday, so it has to be OK.
Also guy from HMRC few days ago took a look at our test server and approved that all works nicely with them.

[s-patompong]

I did change $request_headers to $requestHeaders in Environment class. This is for consistency of the project. I'll find a way to add the rule into StypeCI.

[s-patompong]

PR is merged to master and released as v1.2.0 (https://github.com/s-patompong/hmrc-api-php/releases/tag/v1.2.0)