feat(projects): add archive/unarchive functionality (#168)

Uses this endpoint https://docs.gitlab.com/ce/api/projects.html#archive-a-project

Fixes #166

Author: max-wittig

src/services/Projects.js

@@ -8,6 +8,12 @@ class Projects extends BaseService {
     return RequestHelper.get(this, 'projects', options);
   }
 
+  archive(projectId) {
+    const pId = encodeURIComponent(projectId);
+
+    return RequestHelper.post(this, `projects/${pId}/archive`);
+  }
+
   create(options) {
     const url = options.userId ? `projects/user/${encodeURIComponent(options.userId)}` : 'projects';
 
@@ -93,6 +99,12 @@ class Projects extends BaseService {
     return RequestHelper.put(this, `projects/${pId}/transfer`, namespace);
   }
 
+  unarchive(projectId) {
+    const pId = encodeURIComponent(projectId);
+
+    return RequestHelper.post(this, `projects/${pId}/unarchive`);
+  }
+
   unshare(projectId, groupId) {
     const [pId, gId] = [projectId, groupId].map(encodeURIComponent);