Fixed issue #317

There's no need for the library to replicate a logic when GitHub does
that (and does that correctly.)

Looking at the commit history, I couldn't see why this was added in the
first place.

src/main/java/org/kohsuke/github/GHRepository.java

@@ -505,7 +505,6 @@ public class GHRepository extends GHObject {
     }
 
     private void modifyCollaborators(Collection<GHUser> users, String method) throws IOException {
-        verifyMine();
         for (GHUser user : users) {
             new Requester(root).method(method).to(getApiTailUrl("collaborators/" + user.getLogin()));
         }
@@ -1118,11 +1117,6 @@ public class GHRepository extends GHObject {
 //        return root.retrieveWithAuth("/pulls/"+owner+'/'+name,JsonPullRequests.class).wrap(root);
 //    }
 
-    private void verifyMine() throws IOException {
-        if (!root.login.equals(getOwnerName()))
-            throw new IOException("Operation not applicable to a repository owned by someone else: " + getOwnerName());
-    }
-
     /**
      * Returns a set that represents the post-commit hook URLs.
      * The returned set is live, and changes made to them are reflected to GitHub.