Fallback to en locale + better failure logging and tag_on_failure

Some more improvments to date filter:

use a fallback parser with english locale when platform default is non-english (LOGSTASH-785)
improve register error report with invalid pattern (LOGSTASH-1487)
improve date parsing final failure log (add the config) & tag_on_failure logic (LOGSTASH-777,LOGSTASH-915)

Original PR from https://github.com/elasticsearch/logstash/pull/1682