Check for incorrect transforms in XML signature.
- The SAML2 Core spec section 5.4.4 states what transforms are allowed, check that no others are used.
Fixes after code review of pull request.
- Added comment to Saml2Response_Validate_FalseOnIncorrectTransformsInSignature making clear the wrong transform is used.
- Now using built in constants for XML Dsig URNs.
- Refactored Saml2Response.CheckSignature to make code more readable.
Merge pull request #64 from AndersAbel/55RejectWrongTransforms

Check for incorrect transforms in XML signature.