[RFR]: Added Origin CA Certificate endpoint (#123)

* Added Certificate endpoint

* Implement all calls in /certificates endpoint

* Added to travis more php versions

* Fix package compatibility

* Added CertificateTest

* Added test for Certificate endpoint

* Added more tests

* Updated README

Co-authored-by: haphan <thanhha.phan@myrepublic.net>

src/Configurations/Certificate.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace Cloudflare\API\Configurations;
+
+class Certificate implements Configurations
+{
+    const ORIGIN_RSA = 'origin-rsa';
+    const ORIGIN_ECC = 'origin-ecc';
+    const KEYLESS_CERTIFICATE = 'keyless-certificate';
+
+    private $config = [];
+
+    public function getArray(): array
+    {
+        return $this->config;
+    }
+
+    /**
+     * Array of hostnames or wildcard names (e.g., *.example.com) bound to the certificate
+     * Example: $hostnames = ["example.com", "foo.example.com"]
+     * @param array $hostnames
+     */
+    public function setHostnames(array $hostnames)
+    {
+        $this->config['hostnames'] = $hostnames;
+    }
+
+    /**
+     * The number of days for which the certificate should be valid
+     * Default value: 5475
+     * Valid values: 7, 30, 90, 365, 730, 1095, 5475
+     * @param int $validity
+     */
+    public function setRequestedValidity(int $validity)
+    {
+        $this->config['requested_validity'] = $validity;
+    }
+
+    /**
+     * Signature type desired on certificate ("origin-rsa" (rsa), "origin-ecc" (ecdsa), or "keyless-certificate" (for Keyless SSL servers)
+     * Valid values: origin-rsa, origin-ecc, keyless-certificate
+     * @param string $type
+     */
+    public function setRequestType(string $type)
+    {
+        $this->config['request_type'] = $type;
+    }
+
+    /**
+     * The Certificate Signing Request (CSR). Must be newline-encoded.
+     *
+     * @param string $csr
+     */
+    public function setCsr(string $csr)
+    {
+        $this->config['csr'] = $csr;
+    }
+}