break out the null logger into its own file; update requires

This moves the null logger definition to its own file and updates
references to specifically require this in.  This is more about
cleanup and consistency - no behavior changes.

This is also setup for future logging changes.  There will most likely
be a logger that encapsulates the verbose/summary logging logic
currently living in the logging middleware.  Who knows, the middleware
may dissappear in the future.

Anyway, this is cleanup and prep for those possible future changes.
Merge pull request #142 from redding/kr-logger

break out the null logger into its own file; update requires