Change schema version to 1.2.0 in release notes.
Update dependencies before release.
[maven-release-plugin] prepare release kiji-schema-root-1.2.0
[maven-release-plugin] prepare for next development iteration
SCHEMA-514. Fixed a message formatting problem when deleting all the values from a cell.

review: https://review.kiji.org/r/915/
issue: https://jira.kiji.org/browse/SCHEMA-514