Update root pom version to 1.2.1-S
BENTO-100. CDH5: Update dependency on BentoCluster 2.0.0-S

 - Update BentoCluster dependency to 2.0.0-S
 - Remove kiji-model-repository
 - Remove kiji-scoring-server
 - Update dependency on KijiREST to include the CDH5 version.

issue: https://jira.kiji.org/browse/BENTO-100
review: https://review.kiji.org/r/2145
BENTO-101. Update to latest SNAPSHOT versions of dependencies.

issue: https://jira.kiji.org/browse/BENTO-101
review: https://review.kiji.org/r/2154