In testing and other use cases, the ability to keep a context open
beyond the end of a task can be useful. This change provides the
ability to keep the context alive once a task has completed while also
explicitly shutting the context down (by default) once a task has ended.
Resolvesspring-cloud/spring-cloud-task#102
* Timestamp Demonstrates a Spring boot/task application as a single java file.
* HelloWorld Demonstrates a Spring boot/task application using java configuration.
resolvesspring-cloud/spring-cloud-task#23