Closes #2188 - adds checking whether attachment has a proper taskId set when updating a task.

[nyuuyn]

Closes issue #2188

Release Notes:

If attachments are set a wrong Task Id the API will respond with a BadRequest

For the submitter:

• I updated the documentation and will supply links to the specific files
• I did not update the documentation
• I included a link to the SonarCloud branch analysis
• After integration of the PR, I added a description of changes on the current release notes
• I did not update the current release notes
• I put the ticket in review
• After integration of the pull request, I verified our bluemix test environment is not broken

Verified by the reviewer:

• Commit message format → (Closes) #: Your commit message. i.e. Closes Commit Hooks won't work without JIRA Tickets #2271: Your commit message.
• Submitter's update to documentation is sufficient
• SonarCloud analysis meets our standards
• Update of the current release notes reflects changes
• PR fulfills the ticket
• Edge cases and unwanted side effects are tested
• Readability

[jamesrdi]

This PR is similar to the PR here: #1876

[nyuuyn]

This PR is similar to the PR here: #1876

I added/changed the code to incorporate the changes in the old PR, such as, checking the attachments taskId when updating a task