Rectify the path munging

tools/itango/install_requirements-DS.sh

+if [ ${#} -ne 1 ]; then
+    echo "The 1st parameter must be the requirements.txt file."
+    exit -1
+fi
+
 # Find the path to the device server's requirements.txt file
 # on the Docker's host but relative to the /hosthome directory
 # in Docker the user's # mounted ${HOME}).
 # ATTENTION
 # This is assuming that the device server's requirements.txt file
 # exists # on the Docker's host in the user's ${HOME} directory.
-runThis=$(basename ${0})
-runThis=${runThis}/requirements.txt
-if [ -f ${runThis} ]; then
+requirements=$(basename ${1})
+echo ${requirements}
+if [ -f ${requirements} ]; then
     myDir=${PWD}
 else
-    myDir=${PWD}/$(dirname ${0})
+    myDir=${PWD}/$(dirname ${1})
 fi
-deviceServerPath=${myDir//${HOME}\//\/hosthome\/}
-
-docker exec -it itango python3 -m pip install -r ${deviceServerPath}/requirements.txt
+requirementsPath=${myDir//${HOME}\//\/hosthome\/}
+docker exec -it itango python3 -m pip install -r ${requirementsPath}/${requirements}