Add support for Workflow Runs (#1583)

To build on the previous work supporting querying Workflows for GitHub
Actions, add a class and relevant methods to support querying runs of a
workflow.

github/Repository.py

@@ -136,6 +136,7 @@ import github.Tag
 import github.Team
 import github.View
 import github.Workflow
+import github.WorkflowRun
 
 from . import Consts
 
@@ -3007,9 +3008,24 @@ class Repository(github.GithubObject.CompletableGithubObject):
             list_item="workflows",
         )
 
+    def get_workflow_runs(self):
+        """
+        :calls: `GET /repos/:owner/:repo/actions/runs <https://developer.github.com/v3/actions/workflow-runs>`_
+        :rtype: :class:`github.PaginatedList.PaginatedList` of :class:`github.WorkflowRun.WorkflowRun`
+        """
+        return github.PaginatedList.PaginatedList(
+            github.WorkflowRun.WorkflowRun,
+            self._requester,
+            self.url + "/actions/runs",
+            None,
+            list_item="workflow_runs",
+        )
+
     def get_workflow(self, id_or_name):
         """
         :calls: `GET /repos/:owner/:repo/actions/workflows/:workflow_id <https://developer.github.com/v3/actions/workflows>`_
+        :param id_or_name: int or string
+
         :rtype: :class:`github.Workflow.Workflow`
         """
         assert isinstance(id_or_name, int) or isinstance(id_or_name, str), id_or_name
@@ -3018,6 +3034,21 @@ class Repository(github.GithubObject.CompletableGithubObject):
         )
         return github.Workflow.Workflow(self._requester, headers, data, completed=True)
 
+    def get_workflow_run(self, id_):
+        """
+        :calls: `GET /repos/:owner/:repo/actions/runs/:run_id <https://developer.github.com/v3/actions/workflow-runs>`_
+        :param id_: int
+
+        :rtype: :class:`github.WorkflowRun.WorkflowRun`
+        """
+        assert isinstance(id_, int)
+        headers, data = self._requester.requestJsonAndCheck(
+            "GET", self.url + "/actions/runs/" + str(id_)
+        )
+        return github.WorkflowRun.WorkflowRun(
+            self._requester, headers, data, completed=True
+        )
+
     def has_in_assignees(self, assignee):
         """
         :calls: `GET /repos/:owner/:repo/assignees/:assignee <http://developer.github.com/v3/issues/assignees>`_