Add automatic installation of Python modules

The Python modules that the device depends on have to be
specified in the file requirements.txt in the same path
of the device.

tools/itango/start-DS.sh

@@ -37,5 +37,8 @@ else
     myDir=${PWD}/$(dirname ${deviceServer})
 fi
 deviceServerPath=${myDir//${HOME}\//\/hosthome\/}
+if [ -f ${deviceServerPath}/requirements.txt ]; then
+    docker exec -it itango pip3 install -r ${deviceServerPath}/requirements.txt
+fi
 
 docker exec -it itango python3 ${deviceServerPath}/${runThis} ${instance} ${@}