[NUCLEO_F030R8] Many improvements added

- Automatic clock configuration at startup between HSE and HSI
- System clock = 48 MHz for both
- Configure LSE for RTC (if not available LSI is used instead)
- Add 1MHz clock for I2C
- Update SPI prescaler values
- Typo corrections
Merge pull request #271 from bcostm/master

[NUCLEO_F030R8] Many improvements added