Localization bugfix and compatibility with redmine 2.4

* removed `JournalObserver` patch for compatibility with redmine 2.4
 * *works for me with 2.4.4, ruby 1.9.3-p0, rails 3.2.17*
* Fixes bug where label in Admin > Roles > Settings wouldn't be displayed in current language
 * Localization didn't work because there was no matching string...
* Also: small changes in Readme