Improved http validation with exponential backoff

Added documentation
Simplified HTTP validation flow (no longer need challenge to get file contents)
Updated README.md

src/Data/Order.php

@@ -41,7 +41,17 @@ class Order
      */
     protected $domains;
 
-
+    /**
+     * Order constructor.
+     * @param array $domains
+     * @param string $url
+     * @param string $status
+     * @param string $expiresAt
+     * @param array $identifiers
+     * @param array $authorizations
+     * @param string $finalizeURL
+     * @throws \Exception
+     */
     public function __construct(
         array $domains,
         string $url,
@@ -51,6 +61,10 @@ class Order
         array $authorizations,
         string $finalizeURL
     ) {
+        //Handle the microtime date format
+        if (strpos($expiresAt, '.') !== false) {
+            $expiresAt = substr($expiresAt, 0, strpos($expiresAt, '.')) . 'Z';
+        }
         $this->domains = $domains;
         $this->url = $url;
         $this->status = $status;
@@ -60,41 +74,74 @@ class Order
         $this->finalizeURL = $finalizeURL;
     }
 
+
+    /**
+     * Returns the order number
+     * @return string
+     */
     public function getId(): string
     {
         return substr($this->url, strrpos($this->url, '/') + 1);
     }
 
+    /**
+     * Returns the order URL
+     * @return string
+     */
     public function getURL(): string
     {
         return $this->url;
     }
 
+    /**
+     * Return set of authorizations for the order
+     * @return Authorization[]
+     */
     public function getAuthorizationURLs(): array
     {
         return $this->authorizations;
     }
 
+    /**
+     * Returns order status
+     * @return string
+     */
     public function getStatus(): string
     {
         return $this->status;
     }
 
+    /**
+     * Returns expires at
+     * @return \DateTime
+     */
     public function getExpiresAt(): \DateTime
     {
         return $this->expiresAt;
     }
 
+    /**
+     * Returs domains as identifiers
+     * @return array
+     */
     public function getIdentifiers(): array
     {
         return $this->identifiers;
     }
 
+    /**
+     * Returns url
+     * @return string
+     */
     public function getFinalizeURL(): string
     {
         return $this->finalizeURL;
     }
 
+    /**
+     * Returns domains for the order
+     * @return array
+     */
     public function getDomains(): array
     {
         return $this->domains;