SCORE-129. Repackage ScoringServer into a submodule of KijiScoring

issue: https://jira.kiji.org/browse/SCORE-129
review: https://review.kiji.org/r/1291
Updates to kiji-scoring-server for the new kiji-modeling project.

Signed-off-by: amit <amit@wibidata.com>
Add versions configuration for the scoring server
SCORE-119. Improve FreshenerThreadPool API

issue: https://jira.kiji.org/browse/SCORE-119
review: https://review.kiji.org/r/1293
SCORE-120. InternalFreshKijiTableReader should accept an Executor service as a constructor parameter which would override the default singleton threadpool

issue: https://jira.kiji.org/browse/SCORE-120
review: https://review.kiji.org/r/1294
SCORE-131. Invalid log statement

issue: https://jira.kiji.org/browse/SCORE-131
review: https://review.kiji.org/r/1298
SCORE-130. Adds a mutable, per thread kvstore.

issue: https://jira.kiji.org/browse/SCORE-130