Begin implementation of Enterprise ManagementConsole API, redux (#2010)

* Initial implementation of ManagementConsole - maintenance mode

* Add environment var support for management console password for integration tests

* Add reactive client and unit tests

* Update some xmlDoc

* I think this is a better way to setup the underlying baseUri on IConneciton, to achieve managemet console access rather than requiring a specific GitHubClient that cant call normal API's
Instead, the management client methods can check the base Url and if it contains /api/v3/ they can set their relative endpoint Uri to include a leading "/" which will cause the /api/v3/ to be removed.

* Update EnterpriseClient.cs

Fix xml comments

* Update IEnterpriseClient.cs

Fix xml comments

* Still trying to get the xmDoc perfect, thanks app veyor :)

* XmlDoc'ing my way to success

* Add specific test attribute for management console tests

* check chronic string empty/null

* Use helper's password field in test

* Tidy up maintenance mode tests by using a context/destructor to manage the initial/end state of maintenance mode

* make internal and tidy up URL concatenation

* move GHE endpoint fixup inside ApiUrls methods

* Rework request object to be the correct structure so SimpleJsonSerializer can be used to serialize it.  Remove MaintenanceDate class and just pass in the Date/string for when
Still need to use UrlFormEncoding rather than json in the POST body though...

* Create abstract base class for FormUrlEncoded parameters (similar to existing RequetParameters) and inherit from it in UpdateMaintenanceRequest

* Fix maintenance context logic - destructor should always turn maintenance OFF regardless of initial requested state

* Fix xml comment

* Fix Xml comment

* Those pesky xml comments!

* Fine, I give up!

* Fix string.Format

* fix bad rebase

* fix failing convention tests

* restore missing whitespace

* writing some docs

* some edits

* edit

Octokit.Tests.Integration/EnterpriseHelper.cs

@@ -69,7 +69,7 @@ namespace Octokit.Tests.Integration
         static EnterpriseHelper()
         {
             // Force reading of environment variables.
-            // This wasn't happening if UserName/Organization were 
+            // This wasn't happening if UserName/Organization were
             // retrieved before Credentials.
             Debug.WriteIf(Credentials == null, "No credentials specified.");
         }
@@ -108,10 +108,9 @@ namespace Octokit.Tests.Integration
             get { return Environment.GetEnvironmentVariable("OCTOKIT_GHE_CLIENTSECRET"); }
         }
 
-        public static void DeleteUser(IConnection connection, User user)
+        public static string ManagementConsolePassword
         {
-            if (user != null)
-                DeleteUser(connection, user.Login);
+            get { return Environment.GetEnvironmentVariable("OCTOKIT_GHE_CONSOLEPASSWORD"); }
         }
 
         public static void DeleteUser(IConnection connection, string username)
@@ -162,6 +161,19 @@ namespace Octokit.Tests.Integration
             }
         }
 
+        public static void SetMaintenanceMode(IConnection connection, bool enabled)
+        {
+            try
+            {
+                var client = new GitHubClient(connection);
+                client.Enterprise.ManagementConsole.EditMaintenanceMode(
+                    new UpdateMaintenanceRequest(new UpdateMaintenanceRequestDetails(enabled)),
+                    EnterpriseHelper.ManagementConsolePassword)
+                    .Wait(TimeSpan.FromSeconds(15));
+            }
+            catch { }
+        }
+
         public static IGitHubClient GetAuthenticatedClient()
         {
             return new GitHubClient(new ProductHeaderValue("OctokitEnterpriseTests"), GitHubEnterpriseUrl)