[$100] Make sure transactions work automatically

[maxceem]

As we use continuation-local-storage for Sequelize transactions should work without direct passing the transaction object into the options. And we use this in many places in the project:

Though as per my testings, it feels that transactions didn't work (partials changes weren't reverted in case something failed). But it might be some other reasons as I could make several fixes at once as I was sure that it wouldn't work without directly defining transactions. So as a result in new changes done in this PR #322 I forced passing transactions explicitly:

Todo

1. Make sure that transactions work without explicit passing as we are using continuation-local-storage for Sequelize, see docs.

2. Update code to NOT pass transactions explicitly.

[maxceem]

For the first part we should verify if transactions work or no automatically if we don't define tx explicitly. After we get results of this verification part we would decide what to do next.

1. Update code to not pass transactions directly in the cases when we pass it now.

2. Test case 1. When we update milestone status using PATCH /v4/timelines/:timelineId(\\d+)/milestones/:milestoneId(\\d+) we always create statusHistory records to track the status of milestones. We should make sure that if the transaction failed and we didn't manage to complete update fully, the milestone is not updated and statusHistory record is not created.

   throw error somewhere in the code after milestone is updated and statusHistory record is created inside the transaction. Check that after such error all the object from the transactions was not updated/created in the DB.

3. Test case 2. We have another endpoint which has a bigger and more complex transaction to test POST /v4/timelines.
   If we create a timeline with defined templateId, it would trigger creating the list of milestones for the template using bulkCreate https://github.com/topcoder-platform/tc-project-service/blob/feature/milestone-pausing/src/routes/timelines/create.js#L61-L109

   So for testig, we can create a timeline with the body like the next one:

   {
     "param":{
       "name":"new name",
       "description":"new description",
       "startDate":"2018-05-29T00:00:00.000Z",
       "endDate": "2018-05-30T00:00:00.000Z",
       "reference": "project",
       "referenceId": 1,
       "templateId": 29
     }
   }

   Make sure that you put to referenceId some existent projects.id. And to templateId some existent milestone_templates.referenceId.

   To have some demo data in the DB use the next command from the readme, so you don't have to create templates and project manually: https://github.com/topcoder-platform/tc-project-service#import-sample-metadata--projects

   throw error somewhere in the code after timeline, milestones and statusHistory records are created inside the transaction. Check that after such error all the object from the transactions was not created in the DB.

4. Create 2 demo videos which would demonstrate how Test case 1 and Test case 2 behave: do transaction works after removing tx or no? Provide links to the demo videos.

[mhikeo]

Hi. Kondly assign this to me. Thanks.

[maxceem]

@mhikeo assigned.

[maxceem]

As no comment has been provided during 12 hours as per this [Bug Bash](https://www.topcoder.com/challenges/30095031 rules), this issue is now open for pickup.

[r0hit-gupta]

Please assign me.