Removed WMF configs from BounceHandler extension

* Used $wgExtensionFunctions[] to load in values for extension globals
* Made $wgUnrecognizedBounceNotify point to $wgNoReplyAddress

Bug: 73043
Change-Id: I17050d5995a82bce89d79bbf3bfc06dc6c37e981
Merge "Removed WMF configs from BounceHandler extension"