XML output option in /listkeys

[Marc]

Per Travis' request, I have provided an xml output option for /
listkeys, invoked thusly:

http://cloudcache.ws/listkeys.xml (akey in headers, along with
timestamp and signature, per usual)

It also recognizes /listkeys.json .

As before, if /listkeys is used with no extension, output is in JSON
format.

Once we're ok with the way /listkeys.xml is implemented, I will do the
same for /list (which is a dictionary instead of an unordered set).
Therefore, feedback on /listkeys.xml is most welcomed.

While I'm on the topic, please note that /listkeys may include keys
that are expired, while /list does not - in fact calling /listkeys
immediately after calling /list will exclude any expired keys. If
there is sufficient outcry, we may either make sure that listkeys
excludes any expired keys (with performance hit) or alternatively,
provide an option (via headers or query parm) along the lines of
&exclude-expired=1.

Thanks,


Marc