EXP-136. Implement a trainer for linear regression models.

issue: https://jira.kiji.org/browse/EXP-136
review: https://review.kiji.org/r/1125
Fixup release version and small error message bug.

Reviewed by: robertchu
EXP-203. Pass arguments to model phases

issue: https://jira.kiji.org/browse/EXP-203
review: https://review.kiji.org/r/1141
This version should work
changed flag used from first -> precendence
removed extra scratch file
Use the right configuration keys
update to schema-1.3.0, tests fail