Replace chmod 777 with reasonable permissions

[schrnz]

chmod'ing everything to 777 is an obsolete and dangerous relic from the early times of the project where it was all about getting things done quickly. Now that we want to use ARTist in production systems, we should take care of assigning proper access rights to executable files, such as the resulting instrumented oat file.

The objective is to either dynamically find the correct access rights or find fixed ones that work on a multitude of devices. While the dynamic way is preferable, #11 has shown that it might not always be possible to implement this (easily).

I would assume this is a good first issue if you want to get started with ARTist since you do not have to understand much about the ARTist ecosystem. It is just about finding a way to assign proper access rights to those files that are currently chmod'ed to 777.

[schrnz]

Postponed, will not be part of the beta.