documentation and Python test suite added

Python/runTestSuite.py

+import sys
+# Add the ptdraft folder path to the sys.path list
+sys.path.append('unitTests')
+
+from test_derivatives import test_derivatives
+from test_zeroInitialVelocity import test_zeroInitialVelocity
+
+#run tests
+res = test_derivatives()
+res = test_zeroInitialVelocity()
+