Fix AddCacheDependency signature to use params

The .NET AddCacheDependency method signature is `public void AddCacheDependency(params CacheDependency[] dependencies);` Mono should mirror the signature (even if it isn't implemented) to prevent build errors. Conditional code, of course, will need to be used for an alternative mono path.
Merge pull request #1103 from nathanaeljones/patch-1

Fix AddCacheDependency signature to use params