Adds support for async handlers and preprocessors.
Adds an example for a server with async and sync handlers/processors.
Merge branch 'master' from upstream into future_based_handle
Minor cleanup.
Merge pull request #4 from fkleon/future_based_handle

Future based handles
removed logging_handlers.  created placeholder logging functions.  Will investigate switching to log4dart
switched to log4dart
Merge branch 'master' into isolates

Conflicts:
	lib/dartrs.dart
	lib/src/server.dart
more commits