As a user, when creating defects, the Sprint field should be automatically populated with the current Sprint

When creating defects from the execution screen, the Sprint field should be automatically populated with the current Sprint. 

The Sprint value will be resolved from:
 * The Test Execution if it is directly associated with a Spring
 * Sub-Test Execution if the parent Story is associated with a Sprint.
 * The Story, if the Test Execution does not contain a Sprint but the story is associated with a Sprint.