Add guava dependency
Use LoadingCache to limit no.of open file handles

* Instead of using a HashMap, use Guava LoadingCache to handle the number
  concurrent Parquet writers can be open.
* Default maximum number of writers is 10
Clean up unused file writer
Add 'maxNumberOfWriter' parameter for max open file handles
Update changelog for 1.1.0
Update README for 1.1.0
Bump the version to 1.1.0