absolute IMU class, fails to find ports in new version of ev3dev

[Horsevad]

When trying to generate an instance of class AbsoluteIMU, you can only specify the port as an integer value, and then it checks in /sys/class / ... uevent for LEGO_ADDRESS=in2' but the port name for an the absolute IMU-ACG sensor from mindsensors mounts on port in2:i2c17 or something like this.

Thus the code breaks, when trying to make the sensor. A quick fix is to use .startswith() instead of an exact match.

[Horsevad]

The problem occurs in ev3dev.py around line 229 - 258