As system, the REST API should be able to import results and assign them to a Test Plan

• Whenever executing tests in a CI environment, the reporting of results will normaly lead to a creation of a new Test Execution.
  These Test Executions may be related to a given Test Plan though.
  Thus, the endpoint for importing execution results (POST /rest/raven/1.0/import/execution), should provide a way to optionally specify the Test Plan using a parameter "testPlanKey".

A new field named "testPlan" must be supported by the Xray internal import format. This field must be included within the "info" element.

In case of the cucumber or behave JSON reports, Xray must support a new REST method for importing a multipart request containing both the Cucumber/Behave JSON report and a JSON meta data file containing information of arbitrary fields. These fields must follow the JSON format from the JIRA REST API for creating new issues.