Add support for new cit attributes: csrUploadAllowed and KeyGeneratedByVenafiAllowed

[angelmoo]

Add support for new cit attributes: csrUploadAllowed and KeyGeneratedByVenafiAllowed:

When creating a new policy on VaaS using a policy specification, if policy specification's serviceGenerated attribute is true then KeyGeneratedByVenafiAllowed will be true and csrUploadAllowed will be false And if serviceGenerated is false then csrUploadAllowed will be true and KeyGeneratedByVenafiAllowed will be false
if policy specification's serviceGenerated attribute is not specified, then csrUploadAllowed and KeyGeneratedByVenafiAllowed values will be true

please look at Vcert implementation: Venafi/vcert#201