Renamed to ExcelXLibrary

After a little reading, I found out that the openpyxl only supports
*.xlsx files.

Signed-off-by: Ika Belerma <ika.belerma@gmail.com>
I can now read and return the value of a cell!

Either by active sheet or a sheet name. I just wonder if
I can return non-strings?

Signed-off-by: Ika Belerma <ika.belerma@gmail.com>