Parse excel .xlsx files into arrays and json objects and write them to a file.

• Reads .xlsx files
• Writes .json files
• Can indicate which column to use as the key
• Catches and notifies if an error if .xlsx file doesn't exist or is invalid
• Catches and notifies if requested deleted rows or columns doesn't exist in the .xlsx file but saves the file anyways

$ node app (root-filename) (index-of-column-for-key)

Reads sample.xlsx file by default and uses the first column as the key

$ node app

Reads test.xlsx file and uses the first column as the key

$ node app test

Reads test.xlsx file and uses the 2nd column (index 1) as the key

$ node app test 1