Started on a spec for incremental build improvements.
Added another usecase.
Added a placeholder story to the spec.
Use a separate user home dir for old versions, as they don't isolate meta-data from different repositories.
Build with Gradle 1.5-rc-1
Clean up any wrapper download temp files that may be there because of a simultaneous download by another process.
GRADLE-2699 - use filesystem locks to prevent concurrent wrapper downloads interfering with each other during the unpack step.

Test coverage is inadequate at this stage.
Remove the incubating section from the release notes template and the 1.6 notes.
Build with Gradle 1.5-rc-1
GRADLE-2699 - Bump up our maximum size threshold for the wrapper jar to accommodate the multi process safety code.
GRADLE-2699 - Close all handles to lock files used to make wrapper installation multi process safe before trying to delete them.
GRADLE-2699 - release notes for multi process safe wrapper install.
Fix for tooling API + really old provider versions + ibm jvm 5
Use the supplied user home dir before converting command-line options.
Added some coverage for cyclic project dependencies.
Don't use a remote repo for these cross version int tests, as they use an isolated user home dir.
ported test to spock
more test coverage for DefaultPolymorphicDomainObjectContainer
fixed test
Added toString representations to assist with debugging