Changed approach to handling CSV files.
- Removed CSVHandler.java in favour of CSVObject.java, modeled off the
org.json library's JSONObject. This will be a more intuitive model of
the data contained in a CSV file.
- Adapted CSVHandler.readFile methods into the CSVObject constructors
and copied across useful features (hasData, getExtension(String)).
- Created CSVFileException.java for non-fatal errors with reading CSV
files