Do not provide empty smart constructor - just 'apply' is fine
loadFromFolder: make it fail if not implemented
[sbt Project] Do compilation with extra flags
Add Metadata semantics. Restrict 'ParquetFile' constructors
HDFS: listing of files is now called 'ls'
Util test: shared a non-existent directory name
HDFS.deleteFile -> 'rm' Extra documentation
Util test: stop removing source file on 'mv'
ScalacSettings now contains all Scala compiler flags
Add TODO for work in the future (Rollbacks for operatiosn + better traversal of directories)