Prevent overflow exceptions when status id > int.Max

I have a (private) repository where GitHub reports statuses with
ids like 4299360515, which fail to deserialize as it doesn't fit
on the int.

There is nothing (I could find) on the GitHub API docs that say
that this status id is limited to an int-sized value.

Fixes octokit#1702

Octokit/Models/Response/CommitStatus.cs

@@ -57,7 +57,7 @@ public CommitStatus(DateTimeOffset createdAt, DateTimeOffset updatedAt, CommitSt
         /// <summary>
         /// The unique identifier of the status.
         /// </summary>
-        public int Id { get; protected set; }
+        public long Id { get; protected set; }
 
         /// <summary>
         /// The URL of the status.