Wrong location for data files.

Inside the `install.sql` file.

Most `.csv` files have been referenced correctly *(./data/file_name.csv)* 
but some `.csv` files are not *(file_name.csv)*

so the script is not able to read the data for some table, *(eg - Sales.Customer)*

**Fix**
Change the path for the `.csv` files
`file_name.csv -> ./data/file_name.csv`