adding dependency_decorator
Service container and fleshed out DependencyProvider
Replacing lost import
prototype dependency decorator for timers
Merge remote-tracking branch 'origin/dependencies' into dependency-injection

Conflicts:
	nameko/dependencies.py
merging
improved DependencyProvider and ServiceContainer
allowing dependency decorators to be used without params
Worker pools and WeakKeyDictionary for queue_consumers
merging
SpawningSet for dependencies
import cleanup
merged
adding consumer implementation
flakes
Revert "flakes"

This reverts commit 7dbec209398d6d6d74dd3b735e20e1ab22f435b3.
flakes
Throw errors when raised inside the pool
Merge remote-tracking branch 'origin/dependencies' into dependency-injection

Conflicts:
	test/test_container.py
Core messaging using new publisher and consumers.
Events still based on the old messaging (and therefore  broken)