Implement overwrite process

[benjaoming]

Once #3 is solved, we should be ready to overwrite drives.

(Step zero: Receives a request and generates a new job_id for which the overwrite job progress and results will be collected and store)

1. Gather a "before" sample of data from random sector, store it in the results
2. Perform SMART self test if available
3. Perform ATA Secure Erase if available
4. Fallback to classic wipe 1-pass with zeros if ATA Secure Erase is unavailable
5. Make sure to store progress for current job
6. Sample "after" data (same sample area as "before" data), store it in the results, verify that zeros are read out!