Add a Logstash 'V1' Formatter

https://logstash.jira.com/browse/LOGSTASH-675
Fix a bug and a broken test.

Very embarrassing.
Merge Logstach V1 logic into the main Logstash formatter, add a parameter to the constructor to specify version

Defaults to version '0'.
Remove separate V1 formatter from the read me.
Merge remote-tracking branch 'idio/master'
Formatting fixes