Billing / API: renamed Reward to Payout

`Payout.belongs_to :app_worker`, not `has_one`. This changes a default
route for the resource:
`payouts` → `app-workers/:app_worker_id/payouts`.

Improved the test.

References: [EPMTIOOPS-2954](https://jira.epam.com/jira/browse/EPMTIOOPS-2954).

Author: Alexander-Senko

lib/cirro_io/client.rb

@@ -14,7 +14,7 @@
 require 'cirro_io/client/gig_result'
 require 'cirro_io/client/gig_time_activity'
 require 'cirro_io/client/gig'
-require 'cirro_io/client/reward'
+require 'cirro_io/client/payout'
 
 module CirroIO
   module Client

lib/cirro_io/client/app_worker.rb

@@ -3,6 +3,7 @@ module Client
     class AppWorker < Base
       has_one :app_user
       has_many :gig_invitations
+      has_many :payouts
     end
   end
 end

lib/cirro_io/client/payout.rb

@@ -0,0 +1,7 @@
+module CirroIO
+  module Client
+    class Payout < Base
+      belongs_to :app_worker
+    end
+  end
+end

lib/cirro_io/client/reward.rb

@@ -0,0 +1,48 @@
+RSpec.describe CirroIO::Client::Payout do
+  let(:app_worker) { CirroIO::Client::AppWorker.load id: 1 }
+
+  let :request_headers do
+    {
+      'Accept' => 'application/vnd.api+json',
+      'Accept-Encoding' => 'gzip,deflate',
+      'Content-Type' => 'application/vnd.api+json',
+      'User-Agent' => 'Faraday v1.1.0',
+      'Authorization' => 'Bearer jwt-token',
+    }
+  end
+
+  let :response_headers do
+    {
+      'Content-Type' => 'application/json',
+    }
+  end
+
+  before do
+    configure_api_client
+    allow(JWT).to receive(:encode).and_return('jwt-token')
+  end
+
+  describe '.create' do
+    let(:payout) { described_class.create app_worker_id: app_worker.id, **attributes }
+
+    let(:attributes) do
+      {
+        title: Faker::Hipster.sentence,
+        description: Faker::Hipster.paragraph,
+        'billing-date': Date.today.to_s,
+        amount: 100,
+      }
+    end
+
+    before do
+      stub_request(:post, "#{test_site}/v1/app-workers/#{app_worker.id}/payouts")
+        .with(headers: request_headers)
+        .to_return(body: File.read('./spec/fixtures/payout.json'), headers: response_headers)
+    end
+
+    it 'creates a payout for the app worker' do
+      expect(payout).to be_persisted
+      expect(payout.app_worker_id).to eq 1
+    end
+  end
+end

spec/cirro_io/client/payout_spec.rb

@@ -1,7 +1,7 @@
 {
   "data": {
     "id": "1",
-    "type": "bonus-payouts",
+    "type": "payouts",
     "attributes": {
       "amount": 8969,
       "title": "The Soldier's Art",