simplified test directory and updated test readme

Author: soundanalogous

test/unit/firmata_test/firmata_test.ino renamed to test/firmata_test/firmata_test.ino

@@ -1,7 +1,13 @@
 #Testing Firmata
 
-The Firmata test suite includes unit tests (see the unit directory). Integration
-tests may also be added at some point in the future.
+Tests tests are written using the [ArduinoUnit](https://github.com/mmurdoch/arduinounit) library (version 2.0).
 
-If you make changes to Firmata.cpp, run the tests in /test/unit/ to ensure
+Follow the instructions in the [ArduinoUnit readme](https://github.com/mmurdoch/arduinounit/blob/master/readme.md) to install the library.
+
+Compile and upload the test sketch as you would any other sketch. Then open the 
+Serial Monitor to view the test results.
+
+If you make changes to Firmata.cpp, run the tests in /test/ to ensure
 that your changes have not produced any unexpected errors.
+
+You should also perform manual tests against actual hardware.