CDB-1663 Small XLS/XLSX refactor + bugfix due to problem with multilines.
3 csv_normalizer_spec tests fail, must fix before merging.
CDB-1663 Fixed handling case of 1row-1col for delimiter detection + tests
Merge remote-tracking branch 'origin/CDB-1663' into release/2.10.0

Conflicts:
	services/importer/lib/importer/excel2csv.rb