identifying episode in sorting script

[kierse]

the sorting script first looks for an newzbin ID (to identify newzbin nzbs) then defaults to using the default episode object. This could cause problems in the future with sources such as nzbmatrix (which has its own matching patterns). Update MR to either:

a) loop through list of available sources asking each one if it can handle the given nzb, or
b) use a common naming pattern when adding the nzb to the queue (in scheduling script). Can safely default to default episode object in this case