Merge branch 'release/0.8.0-alpha.7' into develop
Remove obsolete log4j configuration
Replace monadic plan functions with a dynamic var

Change plan-fn to use ordinary clojure functions, and maintain state using a
dynamic var.
Rename phase-pipeline to phase-context
Rename def-plan-fn to def-plan
Rename pipeline-when to plan-when
Add a contributing.md file
Update readme and release notes for 0.8.0-alpha.8
[maven-release-plugin] prepare release pallet-0.8.0-alpha.8
[maven-release-plugin] prepare for next development iteration
Merge branch 'release/0.8.0-alpha.8'