Extended InputRunner to automatically load decoder, and to expose
a Deliver method that supports synchronous or async (i.e. channel
based ) delivery to decoder or direct injection to router. Also added
support for tagging and injecting messages that fail to decode.
Add field containing decode error message to messages that fail
decoding before we send them on to the router.
Use a switch instead of an if-else chain.
Merge pull request #1214 from mozilla-services/decoder_loading

Extended InputRunner to automatically load decoder, and to expose