archive: implement unarchive

made a separate route instead of reusing install route. this was
because we want to copy over all the old app config as much as
possible.

dashboard/public/js/client.js

@@ -1524,6 +1524,16 @@ angular.module('Application').service('Client', ['$http', '$interval', '$timeout
         });
     };
 
+    Client.prototype.unarchiveApp = function (archiveId, data, callback) {
+        post('/api/v1/archives/' + archiveId + '/unarchive', data, null, function (error, data, status) {
+            if (error) return callback(error);
+            if (status !== 202) return callback(new ClientError(status, data));
+
+            callback(null, data);
+        });
+    };
+
+
     Client.prototype.getBackups = function (callback) {
         var page = 1;
         var perPage = 100;