Add driver for TMP102 low-power digital temperature sensor (#141)

* tmp102: add driver and example

tmp102/registers.go

@@ -0,0 +1,18 @@
+package tmp102
+
+const (
+	// Default I2C address
+	Address = 0x48
+
+	// Temperature register address
+	RegTemperature = 0x00
+
+	// Configuration register address
+	RegConfiguration = 0x01
+
+	// Low limit register address
+	RegLimitLow = 0x02
+
+	// High limit register address
+	RegLimitHigh = 0x03
+)