Dockerfile improvements
Dockerfile improvements

- Do not create home directory for webdev user
- Move pip install command ealier in building
- chown and switch to webdev user as last step.

mozilla/sugardough,akatsoulas/sugardough,lmorchard/sugardough,shikhardb/sugardough,akatsoulas/sugardough,glogiotatidis/sugardough,shikhardb/sugardough,lmorchard/sugardough,akatsoulas/sugardough,mozilla/sugardough,glogiotatidis/sugardough,glogiotatidis/sugardough,mozilla/sugardough,shikhardb/sugardough,lmorchard/sugardough