Remove salt provisioning for sd-export files

[emkll]

Closes #271
These tasks should now be done via the securedrop-export package: https://github.com/freedomofpress/securedrop-export

• securedrop-export is uploaded to apt-test-qubes.freedom.press: https://apt-test-qubes.freedom.press/pool/main/s/

Once the above package is uploaded test plan should be as follows:

• Run make clean
• make allcompletes without error
• all tests pass with make test
• USB drive export works
• USB printing works

[zenmonkeykstop]

Built and all tests pass with the exception of the policy one, due to cruft in /etc/qubes-rpc/policy/qubes.VMShell.

File and printer work without error.

Branch needs rebasing against master, however, and should probably be retested. Also the logo PNG is now part of the securedrop-export package and should not need to be added via Salt.

Will rebase and retest.

[conorsch]

due to cruft in /etc/qubes-rpc/policy/qubes.VMShell.

In my experience, such cruft is usually the result of interrupted upgrades, not caused by drift in the branches for this repo. Clean up manually for now—we should aim to provide a more complete solution to the automated logic, however.

File and printer work without error.

🎉! Great news.

Will rebase and retest.

Thanks, agree that's warranted now that we have conflicts, likely due to merge of #305

[zenmonkeykstop]

Rebased and retested:

• make all completes without error
• all tests pass with make test, with the unrelated exception of policy checks due to a bunch of disp-mgmt- rules
• USB drive export works
• USB printing works

Visual inspection of diff looks good. Approved!