Merge branch '2359-formatter-refactored' of https://github.com/Erik-r/yii2-1 into Erik-r-2359-formatter-refactored

* '2359-formatter-refactored' of https://github.com/Erik-r/yii2-1:
  #2359 Bugfix in normalizeDatetimeValue after regression test
  #2359 one test failed in Travis because standard medium date format is different in Travis then on my locale PC.
  #2359 testcases adapted and compatibility to old tests improved
  remove comment lines in asRelativeTime
  Typo in function call #2359
  Namespace corrected #2359
  Refactored formatter class #2359 which works with or without intl extension. Use PHP format patterns alsow with intl. Class is compatible with previous version.