Move directory permission checks inside the container

This is similar to https://github.com/MistySOM/rzg2l/pull/36

I noticed that every time I create a new docker image, I receive an error saying that my cache directory is not writable. So I need to change the ownership of my new cache files from root to myself.

That is because the container is running as root and it creates files as root. The permission check, however, checks for the write-persmission as my user.

So to fix this, in this pull request, I am moving the permission checks from outside the container (ie. run.sh) to inside the container (ie. exec.sh)

MistySOM / rzv2l

Move directory permission checks inside the container #29