Allow controller action/2 to be overridden for custom action handling per #224.
Add documentation for overriding controller action/2
Add Socket get_assign/4 and assign/4 for specific channel/topic access
Refactor channel/topic assigns keys for faster lookup
Make Phoenix.Channel a behavior. Close #225
Add Config.default/1 to lookup default configuration values
Allow Topic garbage collection to be configurable. Close #223
Move config_test to conventional path and bump docs