Add SELinux policy

[Hu6li]

If one tries to run hashr using Linux with enforced SELinux, there will be an access violation when it comes to the preprocessing.
This is due to incompatibility in SELinux contexts of /tmp and docker

AVC Events:
scontext=system_u:system_r:container_t:
tcontext=unconfined_u:object_r:user_tmp_t

General solutions (maybe there are more):

1. Custom SELinux policy
2. Change default preprocessing directory or provide flag to do so
3. Disable SELinux: Don't think this should be a general solution

[meeehow]

Thanks for filing this and sorry for late reply. I like option 2) the most, having this configured via a flag makes most sense. I'll see if I can add the flag in the next couple of days.