Create a separate pool w/ a separate round-robin channel for each decoder type.
Each DecoderSet will grab one decoder of each type that is requested, caching that
decoder for subsequent requests.
Add report for decoder pool channels.
Merge branch 'dev' of github.com:mozilla-services/heka into features/separate-decoder-pools
Merge pull request #172 from mozilla-services/features/separate-decoder-pools

Features/separate decoder pools

r+ trink