added code comment
null checks on ctor params
cleanup DI registration
try to cleanup registration APIs
add another extension method for decorator + default instance
enhance Di to allow named registrations
initial tests for caching
updated cache API to async; reworked default cache
add additional caching extension methods
add caching by default to host
add caching user service; fix autofac config
Merge pull request #667 from thinktecture/di

DI Update