Added publishing functionality to Pubsubhubbub

Added the functionality of sending the alert to Pubsubhubbub.

Right now we have all the valid info only about pubsubhubbub . Will add a broker table later as and when more brokers are available.
That is well the easiest thing to expose the host-parameter in r.url (done).

The other part is not true:
If the request contains a record ID (e.g. /eden/cap/alert/2/publish) then r.url will retain that URL unless you set id=0. So, if you get /eden/cap/alert.cap, then you did have no record ID in the call - and your method didn't have one either.

In fact, your method handler doesn't check whether r.record != None - so I could call /eden/cap/alert/publish without record ID and it would publish all available alerts, i.e. without record ID (not that I think that this is wrong, just pointing out that there are cases where you do /not/ insert a record ID with the regex either).

The actual reason why I suggest using r.url is that r.method may not come from the current.request URL - it could just be set directly (r.method = "publish") in the prep, or the whole S3Request is handcrafted in a completely different controller/method handler, e.g. if it due to some other workflow indirectly produced a cap alert, and now wishes to chain the publishing workflow by calling your method handler directly.

"r" represents the request you're processing - and that /can/ be current.request, but it could also be handcrafted. Thus, you should avoid to tie things to current.request.