Feature direct backend

[nagendramishr]

Proxy:

• Performance improvements in server for Probe path and header checks
• Bug fix when checking for change config parameters
• Spindown old hosts that are no longer in the config
• De-register old hosts from the global circuit breaker when removed
• Bug Fix for gov cloud default credential
• Add MaxEvents to control how many undrained events can be in memory
• Slow down the incoming requests as we start to use up the event buffer