patch from Carlos Canau <Carlos@Canau.COM>
Merge pull request #133 from msimerson/greylisting

patch from Carlos Canau
Merge pull request #130 from msimerson/master

address: added tests for Address::canonify
Consolidate greylist exclusions into exclude()

This makes for an easily overridden method for excluding hosts from greylisting with custom rules
Add missing $self and explicit return
Add tests
Merge pull request #135 from jaredj/consolidate_exclusions

Consolidate greylist exclusions into exclude()
Add RFC link
Merge pull request #136 from jaredj/master

Add RFC link