KIJI-854. Create MapReduceJobOutputs class that works like
MapReduceJobInputs.

This commit modifies a call to a MapReduceJobOutput format from
the default constructor (now private) to an initialization
method in MapReduceJobOutputs.

Reviewed by: robertchu
Exp-91. Removes filters from the model environment.

Reviewed by: Kiyan A.
EXP-77. Allow Hadoop -D flags to be passed from the command line.

This commit modifies the express script so that any left-justified
Hadoop -D flags the user specifies to their scripts or compiled jobs
are properly shuttled to Scalding's Tool, so they are properly
reflected in the configurations of jobs launched.

Reviewed by: robertchu