Malware categorization: windows.svcdiff

[SolitudePy]

Categorize windows.svcdiff as windows.malware.svcdiff

• no dep fixes applied
• since this plugin doesnt have a run() method the wrapper must inherit from the same base class
• __init__ method included since its skipped when copying methods.

[ikelos]

I'm not sure this is worth splitting away from SvcScan (which is what it's based on) to put it under the malware category. One for @atcuno to speak to...