Added index property to Recurrence (simshaun#110)

* Added an index property to Recurrence

* Added test for index

* Removed typehint

* Added intial index property

Fixes simshaun#106

Fix the date format for the Dutch language (simshaun#102)

Basic Spanish Translation (simshaun#100)

* Basic Spanish Translation

* added day_month function to es translation

Account for start date in text transformer to make for clearer output (…

…simshaun#101)

Fix broken Travis, PHP 5.3

Minor tweak to README for v1

Throw exception if rrule with nth BYDAY and unsupported frequency

Danish translation (simshaun#97)

* Added Danish translation

* changes da translation

Added dutch language (simshaun#96)

* Added dutch language
* Update nl.php