Switch to slf4j.

Also re-organize imports in the affected classes according to
project standards.
Switch logging implementation to logback.
Add a servlet listener to destroy the logging context on shutdown.

See http://logback.qos.ch/manual/configuration.html#stopContext
Clear MDC after LoggingFilter has finished.
Move logging related files to their own package.
Unify all authentication and authorization into one interceptor.
The security interceptor is now only invoked on HTTP-enabled methods.

Specifically, the interceptor only operates on methods that are
annotated with @GET, @DELETE, @PUT, @POST, @OPTIONS, @HEAD or
@HttpMethod.
Provide methods to enable and disable debug logging for an org.
Use RestEasy to determine if we need to intercept.
Switch this class to slf4j.
Set default to DEBUG instead of ALL.
Add spec and unit tests for org logging.
Add unit test for custom logback filter.
Merge pull request #433 from candlepin/awood/slf4j

Awood/slf4j