Add possibility to run subset of tests using pattern

This enables running single test or subset of tests from command line using a name pattern.
Not sure about the naming of the project property though. Naming suggestions are welcome :)

Usage:
`./gradlew test -PtestIncludePattern=**/*SimpleTestClone*`
not this PR's issue but note for @novoda/novoda-all we might want to include `testRunTask.include '**/*Tests.class'`