Testing:'pawsapp' user does not have write access to /app and children

[c-simpson]

#314 adds a user pawsapp for running uWSGI. This causes a problem because pytest can't write test results under /app/.pytest_cache/v/cache which is owned by root:

drwxr-xr-x 3 root root 4096 Mar 10 20:07 .pytest_cache

For this, we could

• change directory permissions in the Dockerfile
• tell pytest to use a different directory (and create it in Dockerfile)
• use config to tell pytest not to cache results (probably easiest)

Are there similar cases we might run into?

[c-simpson]

We also need to make /var/lib/server/data owned by pawsapp for logging. (#282)