updated get_findings to work with csv string list

[AaronButler-Veracode]

Findings get_findings method was not working with a csv style list of scan types.

[tjarrettveracode]

Hi @AaronButler-Veracode -- for this change I’d prefer to introduce a separate class for the CWE related endpoints since they’re not strictly related to Findings. Something like:

class CWE():
        def get(self, cwe_Id):
                 return #api call here

Let me know if this makes sense. Thanks.

[tjarrettveracode]

Also we’ll need to update the documentation for a new method.