change response for shared.ops.sleep, save user in POST /user/sleep and add integration tests for it

test/api/v3/integration/user/sleep.test.js

@@ -0,0 +1,27 @@
+import {
+  generateUser,
+} from '../../../../helpers/api-integration/v3';
+
+describe('POST /user/sleep', () => {
+  let user;
+
+  beforeEach(async () => {
+    user = await generateUser();
+  });
+
+  it('toggles sleep status', async () => {
+    let res = await user.post(`/user/sleep`);
+    expect(res).to.eql({
+      preferences: {sleep: true},
+    });
+    await user.sync();
+    expect(user.preferences.sleep).to.be.true;
+
+    let res2 = await user.post(`/user/sleep`);
+    expect(res2).to.eql({
+      preferences: {sleep: false},
+    });
+    await user.sync();
+    expect(user.preferences.sleep).to.be.false;
+  });
+});