Updating CHANGELOG.txt to include fix for Equals() on class substitutes.
Updating CHANGELOG.txt to include fix for Equals() on class substitutes.

jannickj/NSubstitute,jbialobr/NSubstitute,mrinaldi/NSubstitute,jbialobr/NSubstitute,mrinaldi/NSubstitute,huoxudong125/NSubstitute,huoxudong125/NSubstitute,dnm240/NSubstitute,jannickj/NSubstitute,jannickj/NSubstitute,iamkoch/NSubstitute,jbialobr/NSubstitute,paulcbetts/NSubstitute,huoxudong125/NSubstitute,mrinaldi/NSubstitute,jannickj/NSubstitute,dnm240/NSubstitute,dnm240/NSubstitute,paulcbetts/NSubstitute,mrinaldi/NSubstitute,iamkoch/NSubstitute,paulcbetts/NSubstitute,jannickj/NSubstitute,huoxudong125/NSubstitute,jbialobr/NSubstitute,iamkoch/NSubstitute,jbialobr/NSubstitute,dnm240/NSubstitute,paulcbetts/NSubstitute,dnm240/NSubstitute,iamkoch/NSubstitute,huoxudong125/NSubstitute,mrinaldi/NSubstitute,iamkoch/NSubstitute