Merge branch 'release/0.3.0' into develop
Depend on clojure 1.4 and remove slingshot
Update logback test configuration to use encoder

The layout element is no longer valid.
Updated release notes and readme for 0.3.1
[maven-release-plugin] prepare release pallet-common-0.3.1
[maven-release-plugin] prepare for next development iteration
Merge branch 'release/0.3.1'