Update get image tests

*Updated get_image module
-Updated tests due to behavior, fixture and config changes
-Added get_image_after_successful_import test
-Added verify_object_and_imported_exported_image_content test
-Removed redundant get_image_after_successful_import test
-Removed verify_object_and_imported_exported_image_content test
*Updated get_image_negative module
-Updated tests due to behavior, fixture and config changes
*Updated get_image_file module
-Added verify_object_and_imported_exported_image_content test

Change-Id: Ie51ea84bec038be2e9fdd6e3771dd4cf37b8ed80