Added a step to define an issue with a list of attributes.

Example:
And there are the following issues with attributes:
      | subject     | project        | author  | watched_by |
      | Test-Issue  | tested_project | bob     | bob        |
      | NOT-WATCHED | other_project  | bob     | bob,mary   |
Merge pull request #314 from opf/features/issues_with_attributes_step

Added a step to define an issue with a list of attributes.