Add new functions for faster permissions setting

[kierenevans]

• Add common methods to set permissions so we can extend it in the future to include setfacl if possible.
• Use find to speed up permissions setting by finding files and directories not owned by the right user/group or not the right permissions - this helps a lot when using volumes!

[sroze]

That's a very good idea! What's blocking this PR?

[sroze]

@kierenevans do you think you'd have some time at some point to go forward with this issue? Waiting a long time at every container start on the chown -R build:build /app/ command is quite a disruption on projects.