add scalding-hraven module, hRaven-based reducer estimation
add missing hbase dependency
don't double-define Config params, clean up imports, comments
Merge branch 'develop' into bholt/hraven-reducer-estimator
run hraven tests on travis (if we end up having any)
get api hostname from config, other minor changes from feedback
refactor into generic HistoryService/RatioBasedReducer and HRavenHistoryService
add hRaven client config params, some comments
make 'fetchPastJobDetails' return 'Try'
Merge branch 'develop' into bholt/hraven-reducer-estimator
make ReducerEstimator a monoid
use thread classloader, remove fallback estimator, conditionally set flow step strategy
use 'Config.addReducerEstimator' in test
catch possible IOException when fetching flows
fix compile error in estimator instantiation
allow fetching multiple history entries
move RatioBasedEstimator to its own file and make it average multiple histories
make threshold a config parameter, make maxHistory a shared config parameter
make FlowStepHistory a sealed trait so it can be extended in the future
wrap everything in trys