Writing test file to /dev/null, uploading from DD output

[JayGoldberg]

Low resource IoT devices don't have the storage to keep a 100mb file. We can write those to /dev/null.

For upload, instead of uploading 100mb from disk, we can launch dd and pipe that output into a FIFO and read from that with curl.

Also, these devices don't do well under frequent writes, the storage is not meant to be constantly rewritten, it has finite life.