Added review_state_title substitution variable

- This is usefull when triggering a workflow change and you send an
  email letting the person know of the new review_state which is more usefull
  rather then seeing the review_state id
Corrected review_state_title in README.txt
Wrap ReviewStateTitleSubstitution return in a translation factory call
Merge pull request #2 from ichim-david/master

Added review_state_title substitution variable