detailed error message

fix to show more detailed error message
.
[ CLASS ] serial_i2c.regWrite(), serial_i2c.getBase

- fixed serial_i2c.regWrite() to write data to I2C register
- added serial_i2c.getBase()
error, mbedI2C() call, code formatting

- fixed to show more detailed error message
- mbedI2C() call fixed(was passing wrong argument)
- code formatting