Refactor plugin implementations out of pipeline package.
Merge branch 'dev' into pipeline-reorg
Remove no longer used RouterInChanLength method.
Last bits of pipeline reorg clean-up: removed some overkill
all_specs_test.go files, audit the docs, updated changelog, moved all
plugin registration to close to the plugin implementation, caught a
test suite that wasn't being run.
Merge pull request #556 from mozilla-services/pipeline-reorg

Pipeline reorg