first version
moved export and import and now taking parameters
fixed export
new import and export with base column
fixed after splitting to Export/Exporter and Import/Importer
little bit of clean up
Now indexing both JSON and xlsx files when importing to make sure that the same key is not used twice with the same base.

Testing a bit more.
Fixed case
Moved files around
Merge pull request #2 from mWater/import-export-xlsx

Import export xlsx