keep out log4j dependency since slf4j backend should be decided by application not library (also its already on hadoop classpath and slf4j complains when multiple versions of backend are detected on classpath)
Merge pull request #636 from tresata/feat-no-log4j-deps

keep out log4j dependency since slf4j backend should be decided by appli...
Prefer to use sumOption to take advantage of algebird optimizations
Make LzoTraits extend TypedSink and LocalTapSource.
Merge pull request #638 from azymnis/lzo_trait_typed_sink

Make LzoTraits extend TypedSink and LocalTapSource.
Merge pull request #637 from twitter/sumOption

Prefer to use sumOption to take advantage of algebird optimizations