Drivers for invoice/tickets fiscal printers (Epson & Hasar) Argentina
- driver.py: it manage communication protocol
- generic.py: it's an abstract interface for printer implementation
- epson.py: implementation for Epson's printers
- hasar.py: implementation for Hasar's printers
- Improve documentation
- PEP8
- make python3 compatible
- code cleanup
- Unit tests