Updated get_images test file to add new test

* Added new test method 'test_get_images_after_import_task' to verify
* list images returns imported image with status 'active'

Change-Id: I87c9dd04a60a3f0823977812ab77058f6414b4e9
Added new tests files

* Added new negative test under test file 'TestCreateImportTaskNegative'
* Added new positive test under test file 'TestDeleteTask'

Change-Id: Ic0fe3973f0ee780dbcf045e809c6aec344188301
Merge "Updated get_images test file to add new test"
Merge "Added new tests files"