Async polyglot unit testing for Vert.x.

See https://github.com/vert-x3/vertx-unit/blob/master/src/main/asciidoc/java/index.adoc

• find a way to configure junit runner timeout
• when asserting
  • check the same context is used when running with a context (configurable)
  • ensure that any assert is done before the completion of a test, at the moment we are doing that but only in the case of failure
• provide subtest programming model (i.e add a tests in a test)
• consider making TestResult an @DataObject instead
• add closeable resource to register for automatic cleanup or do something like this
• see how to extend state sharing to non json / non basic
• filtering
• handle reporter/formatter failures
• same name test replaces previous ?
• json stream reporter
• reporters
  • xunit
  • markdown
  • tap http://en.wikipedia.org/wiki/Test_Anything_Protocol