minimum needed to allow updating recovery key

Added try/except to check for pre-existing computer, based on serial,
only inserts new recovery key value. Fixed quick typo while I was there
(in the json response.)
Smoke came out of my ears since I’m still green at django, so this is
all I’m pushing for now
Merge pull request #2 from arubdesu/miniFeature-allowRecoveryKeyUpdate

minimum needed to allow updating recovery key