Updated ipaaca helper scripts:

ipaaca-iu-sniffer optionally takes a list of category arguments
(if not specified, it still listens for everything).
ipaaca-iu-injector needs to be provided with a category name
and, optionally, with key-value pairs for the payload, as such:
$ ipaaca-iu-injector  murmlfile  data  smile_3sec.us