Merge pull request #315 from ChristophGr/maven_local_system_property

allow mavenLocal-path to be modified via System-property
Added tests for platform target
Fixes failing test
Polishing of 'maven.repo.local' system property support contribution.

+review
Add a story to more aggressively reuse plugin implementation details during a build.
Indent
Correct precedence of maven location settings.
imports.
Change naming to be consistent, adds docs
Fixes style
CodeNarc fix
Remove unused imports
update wrapper on release branch to use 2.1-rc-1
Some spec work on inputs to DSL rules.
Manually inject JavaToolChain into JavaCompile and Javadoc.
Getter injection cannot be used because we also need a setter for toolChain property on these classes.

+review REVIEW-5158
Merge branch 'release' of github.com:gradle/gradle

Conflicts:
	gradle/wrapper/gradle-wrapper.jar
	gradle/wrapper/gradle-wrapper.properties
Move Javadoc task related classes to language-java

+review REVIEW-5165
ensure custom gradle user home is used (also by older gradle wrappers)

+review REVIEW-5166
Garbage collected some completed stories.
Garbage collected a completed story.