Install ptvsd by default (#217)

* builder: Install ptvsd by default

* builder: Add ptvsd version check

builder/image-software.sh

@@ -153,6 +153,10 @@ cp -R node-v10.15.0-linux-armv6l/* /usr/local/
 rm -rf node-v10.15.0-linux-armv6l/
 rm node-v10.15.0-linux-armv6l.tar.gz
 
+echo_stamp "Installing ptvsd"
+my_travis_retry pip install ptvsd
+my_travis_retry pip3 install ptvsd
+
 echo_stamp "Add .vimrc"
 cat << EOF > /home/pi/.vimrc
 set mouse-=a

builder/test/tests.sh

@@ -12,6 +12,10 @@ python3 --version
 ipython --version
 ipython3 --version
 
+# ptvsd does not have a stand-alone binary
+python -m ptvsd --version
+python3 -m ptvsd --version
+
 node -v
 npm -v