hospital-wsgi collects results previously computed by daemon process

[benoitbryon]

At the moment, hospital-wsgi performs checks on demand. Checks take some time to execute.
Could be:

• checks are executer by another process (a daemon? cronjob? periodic task?)
• this "other process" writes results somewhere, typically to a file
• hospital-wsgi reads the results. Perhaps could be done with "python -m SimpleHTTPServer" too ;)

In this use case, clients do care of:

• "healthchecks" web service response is fast
• "healthchecks" status is timestamped, i.e. we can tell "status was OK less 5 seconds ago" or "status was KO less than one minute ago".