Use ParquetRecordWriter instead of Internal Writer
Fix corrupted output by setting 1 active writer

This is digusting fix yet I can't find out why the heck that if there are more
than 1 writer:
* The output files are corrupted
* The buckets are filled in incorrectly.

Also the cache is useless now since only 1 writer will be active at all time.
Update README and CHANGES to 1.1.1
Update the pom.xml to version 1.1.1