Merge branch 'dev'
First batch of new docstrings.
Move the closure of the `FileMonitor.NewLines` channel (which triggers closure of
the `LogFileInput` itself) into the `FileMonitor` so we're not relying on scheduler
internals to have things happen in the correct order.
Merge branch 'dev' into features/doc-string-audit
Doc strings for config.go and decoders.go.
Add docstrings for filters.go.
Removed (obsolete) TimeoutError definition.
Tweak to a filter doc string, added doc strings to inputs.go.
Remove unused LogfileInput attribute.
Doc strings for LogfileInput.
Add initial LogfileInput tests, and add configurability to the file reading intervals so
the tests can still run quickly.
Merge pull request #117 from mozilla-services/features/logfile-input-tests

Initial LogfileInput tests
Tweak for correctness in inputs.go, add docstrings to outputs.go.
Adjust to fewer log file lines.
Add pipeline_runner.go doc strings.
Doc strings for router.go.
Merge branch 'dev' into features/doc-string-audit

Conflicts:
	pipeline/logfile_input.go
Add circular buffer support to the Lua sandbox
Allow inject_message() to provide some metadata about the payload

- payload_type, defaults to "txt"
- payload_name, defaults to ""
Merge branch 'features/doc-string-audit' into dev