Adding archival support for Repository.edit (#843)

Fixes ##840 

Adding archival support to Repository.edit

No unit tests are included for this change because while you can archive a repository via the edit API, there is no way to un-archive a repository via the edit API.  (See: https://developer.github.com/v3/repos/#edit )

github/Repository.py

@@ -1161,7 +1161,7 @@ def delete(self):
             self.url
         )
 
-    def edit(self, name=None, description=github.GithubObject.NotSet, homepage=github.GithubObject.NotSet, private=github.GithubObject.NotSet, has_issues=github.GithubObject.NotSet, has_wiki=github.GithubObject.NotSet, has_downloads=github.GithubObject.NotSet, default_branch=github.GithubObject.NotSet):
+    def edit(self, name=None, description=github.GithubObject.NotSet, homepage=github.GithubObject.NotSet, private=github.GithubObject.NotSet, has_issues=github.GithubObject.NotSet, has_wiki=github.GithubObject.NotSet, has_downloads=github.GithubObject.NotSet, default_branch=github.GithubObject.NotSet, archived=github.GithubObject.NotSet):
         """
         :calls: `PATCH /repos/:owner/:repo <http://developer.github.com/v3/repos>`_
         :param name: string
@@ -1172,6 +1172,7 @@ def edit(self, name=None, description=github.GithubObject.NotSet, homepage=githu
         :param has_wiki: bool
         :param has_downloads: bool
         :param default_branch: string
+        :param archived: bool. Unarchiving repositories is currently not supported through API (https://developer.github.com/v3/repos/#edit)
         :rtype: None
         """
         if name is None:
@@ -1184,6 +1185,7 @@ def edit(self, name=None, description=github.GithubObject.NotSet, homepage=githu
         assert has_wiki is github.GithubObject.NotSet or isinstance(has_wiki, bool), has_wiki
         assert has_downloads is github.GithubObject.NotSet or isinstance(has_downloads, bool), has_downloads
         assert default_branch is github.GithubObject.NotSet or isinstance(default_branch, (str, unicode)), default_branch
+        assert archived is github.GithubObject.NotSet or (isinstance(archived, bool) and archived is True), archived
         post_parameters = {
             "name": name,
         }
@@ -1201,6 +1203,8 @@ def edit(self, name=None, description=github.GithubObject.NotSet, homepage=githu
             post_parameters["has_downloads"] = has_downloads
         if default_branch is not github.GithubObject.NotSet:
             post_parameters["default_branch"] = default_branch
+        if archived is not github.GithubObject.NotSet:
+            post_parameters["archived"] = archived 
         headers, data = self._requester.requestJsonAndCheck(
             "PATCH",
             self.url,