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.
Heh.  No, I mean the indent isn't the same on all the lines -- the _class, _id, _value lines are one space more indented.  We've gradually been standardizing on indent to just within the enclosing bracket, like the export_btn above.