Hcsr04sensor

- Update hcsr04.py. Replace depracated methods with new ones.
- Add unittest for hcsr04.py script

- Removed RPi.GPIO Install required in setup.py and added apt package install to instructions
in the README.md
- Support for bdist_wheel installs of hcsr04sensor

- pin to the latest version of RPi.GPIO (v.0.7.0)

- force hcsr04sensor to use a specific version of RPi.GPIO in setup.py. Currently uses

- Remove rounding from library. Must now be handled by your application
- Deprecated functions (will be removed in future versions)
depth_metric, depth_imperial, distance_metric, distance_imperial
have been replaced with depth and distance
- Add methods to calculate:
- liquid volume of a cuboid (square or rectangular)
- liquid volume of a standing cylinder
- liquid volume of a cylinder on its side
- liquid volume of an elliptical standing cylinder
- liquid volume of an elliptical cylinder on its side

- basic_distance now a staticmethod on the Measurement class. This method
reads directly from RPi.GPIO. No sample sizes or speeds. Metric only.
No pin cleanups. That should all be handled by your code.
- Changes to recipes to remove rounding
- Many new recipes added for different tank types
- Change to hcsr04.py to remove rounding
- Add recipes for standing cylinder volume and cylinder volume side
- Add tests for all measurements

Add a static basic_distance function to sensor.py. This was added by request.
See README for details