Update the pip install path for local installs

[thekaveman]

Do we need to update this path too or no?

docker-python-web/appcontainer/Dockerfile

Lines 37 to 38 in 5f949ca

	# update PATH for local pip installs
	ENV PATH "$PATH:/home/$USER/.local/bin"

Originally posted by @angela-tran in #42 (review)

@angela-tran you were right! When we enable WEBSITES_ENABLE_APP_STORAGE it overwrites the /home directory, including /home/.local where these packages get installed.

We can use the PYTHONUSERBASE variable to change the directory for user pip install, and then update the PATH accordingly.