bugfix: dsconfig on loggers trigger thread leaks

When applying configuration changes, the code was leaking AsynchronousTextWriters and ParallelTextWriters.
These two classes create threads in their constructors.
Leaking such objects end up creating way too many threads which in turn have a bad effect on the whole system.

Text*LogPublisher.java:
In applyConfigurationChange(), make sure:
- no [Asynchronous|Parallel]TextWriters are leaked
- the logic applying the changes only creates new objects when necessary
Added methods useAsyncWriter(), hasAsyncConfigChanged(), hasParallelConfigChanged().