Create requirements.txt if it doesn't exist (#647)

* Create requirements.txt

This resolves:
Could not open requirements file: [Errno 2] No such file or directory: 'requirements.txt'
The command '/bin/sh -c python3 -m pip install -r requirements.txt' returned a non-zero code: 1

* Create requirements.txt if it doesn't exist

This resolves:
Could not open requirements file: [Errno 2] No such file or directory: 'requirements.txt'
The command '/bin/sh -c python3 -m pip install -r requirements.txt' returned a non-zero code: 1

configureWorkspace/configure_python.ts

@@ -32,6 +32,7 @@ WORKDIR /app
 ADD . /app
 
 # Using pip:
+RUN if [ ! -f requirements.txt ]; then pip3 freeze > requirements.txt; fi
 RUN python3 -m pip install -r requirements.txt
 CMD ["python3", "-m", "${serviceNameAndRelativePath}"]