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"))
```
So, do you mean just add another method named: ```ExcludeScripts(params string[] scriptNames)``` to the FilterFactory class in addition to the existing two? If so yes that makes sense.