Update Constants.cs

Merge pull request AuthorizeNet#181 from rahulrnitc/master

Updating SDK version to 1.9.3 for new release

Update SDKVersion to 1.9.2

Merge pull request AuthorizeNet#164 from AuthorizeNet/future

Merging Future into master for Q4 API updates

Update AuthorizeNet.nuspec

Update AuthorizeNet.nuspec

Update AuthorizeNet.nuspec

Update AuthorizeNet.nuspec

Update AuthorizeNet.nuspec

Update AuthorizeNet.nuspec