Our setup.py no longer has yes/no prompt

Now that we insist on NumPy (expect on Jython/IronPython),
setup.py will not prompt for continuing if NumPy is missing.

.travis-tox.ini

@@ -70,10 +70,9 @@ deps =
     {py27}: networkx
     {py36}: matplotlib
 commands =
-    #The bash call is a work around for the pipe character
-    #The yes is in case we get our prompt about missing NumPy
+    #The bash call is a work around for special characters
     #The /dev/null is to hide the verbose output but leave warnings
-    bash -c \'/usr/bin/yes | python setup.py install > /dev/null\'
+    bash -c \'python setup.py install > /dev/null\'
     #The bash call is a work around for the cd command
     nocov: bash -c \'cd Tests && python run_tests.py --offline\'
     #See https://codecov.io/ and https://github.com/codecov/example-python