Merge pull request #63 from BiffoBear/add-0x-to-error-msg

Added 0x prefix to i2c addr in "No I2C device at address:" err msg.

Author: ladyada

adafruit_bus_device/i2c_device.py

@@ -177,6 +177,8 @@ def __probe_for_device(self):
                 result = bytearray(1)
                 self.i2c.readfrom_into(self.device_address, result)
             except OSError:
-                raise ValueError("No I2C device at address: %x" % self.device_address)
+                # pylint: disable=raise-missing-from
+                raise ValueError("No I2C device at address: 0x%x" % self.device_address)
+                # pylint: enable=raise-missing-from
         finally:
             self.i2c.unlock()