Merge chunks of original pull request #40 from drawks/0.9.x

Add different write ordering behaviors
Add FORWARD_ALL parameter to aggregator
Refactor hashing for clarity

Conflicts:
	conf/carbon.conf.example
	lib/carbon/aggregator/receiver.py
	lib/carbon/cache.py
	lib/carbon/conf.py
	lib/carbon/protocols.py
	lib/carbon/util.py
	lib/carbon/writer.py
Fix tests on 2.6