Renaming to improve maintainability

Classed renamed:
Input and Gazetteer 'ColumnNames' renamed to 'ColumnHeaders' to reduce
confusion with location names.
'GazetteerLocationNames' renamed to 'GazetteerNames'
'FuzzyMatch renamed to 'SuggestedMatch' to make the usage clearer.
Separate folder added for the file access classes

File Import and File Export classes moved to a separate folder for
clarity
Readme updated: Phase 2 complete