BUGFIX: Correct after_fork semantics

After fork SiteSettings was not getting a new process id,
causing site settings not to refresh properly in unicorn

This code also centralizes the logic
PERF: use before suite vs before file
BUGFIX: correctly punch through settings to local provider
Stop using global vars where not needed
Simplify local process site setting provider
Stop setting up methods over and over
Centralize cache clearing
BUGFIX: when RTT is short likes may not appear to work
BUGFIX: site settings db provider not triggering updates
  at the correct point