Filtering Scripts

This is the FilterFactory implementation with Unit Tests as I have proposed for #54 

Usage of the FilterFactory class would be:

```csharp
.WithScriptsEmbeddedInAssembly(Assembly.GetExecutingAssembly(),
 FilterFactory.ExcludeScriptNamesInFile("scriptnames.txt"))
```
I think maybe we should add `ExcludeScripts(params string[] scriptNames)`, I think it will make it clear what the usage is from the public API. (seeing both overloads and one takes an list of script names will make it more clear the intention of the other methods?