When JUnit tests have assumption failures, treat them as "skipped"

JUnit has a conception of "assumptions", when encode conditions in which a test is meaningful.
When an assumption fails, it means that the test provides no useful information, and should
"halt and be ignored".  Prior to this change, Gradle was treating JUnit tests with assumption
failures as "passed".

http://junit.sourceforge.net/javadoc/org/junit/Assume.html
Add unit test coverage for JUnit assumption handling
Add integration test coverage for JUnit assumption handling
Made notify-send notifications transient so that they don't clutter notification panel in Gnome Shell
More integration tests for maven-publish
* Nothing published when no component defined (without java plugin)
* Jar artifact is successfully generated with 'assemble'
* Only dependencies from 'compile' and 'runtime' configuration are included in published pom
Moved maven-publish integration tests to live together
Better integration test for maven-publish and multiple projects
Added test for auto-tested samples in javadoc of Maven project
* Fixed sample code to apply java plugin
Integration test for new maven-publish sample
Cross version test for consuming maven module published with maven-publish plugin
Polishing maven publication
MavenPublication is no longer Buildable
Some fixes for handling restricted characters in text content.
Moved int test to live in core.
Fixed Library.spec.include(Iterable<File>)
Fixed unit test.
Use nightly build again, to collect some diagnostics.
Switched back to 1.3 again.
Moved handling of indentation in SimpleXmlWriter, and use platform line separator in generated xml.
Add the concept of the “test directory” to the GradleExecuter interface, which allows thinning stuff out of GradleDistributionExecuter and generally simplifying things.