Remove DecoderSet abstraction (and `DecoderSet()` method in the
PluginHelper interface) and replace it with Decoder and DecoderRunner
methods that will create and return a decoder or a runner by name.
refactoring tests to use platform specific pipe commands for linux, darwin and windows
extended the inputs_test for ProcessInput for debugging
added CR to the last token Pipe test for Windows
repointed the lpeg tarball to use people.mozilla.com as the original site seems to be down or gone
renamed platform specific test files to match build constraint guidelines :  http://golang.org/pkg/go/build
MultiDecoder needs to support WantsDecoderRunnerShutdown for the
subdecoders.
Simplifies the code to always use the DecoderRunner channel for
decoding.
Dealing with unwrapped Decoders is tricky, so let's give a warning, and
let's not expose the Decoder method on PluginHelper.
Merge pull request #507 from crankycoder/features/fix-process-chain

Refactored ProcessInput and ProcessChain tests to fix cross-platform issues
Merge pull request #506 from mozilla-services/no-mo-decoderset

Remove DecoderSet abstraction (and `DecoderSet()` method in the
Revert borked change to AMQPInput that slipped through.
Merge branch 'dev' into stop-test-goroutines