Fix copying/installing of OpenSSL for XNAT
Fix copying/installing of OpenSSL for XNAT

Use the following CMake cache variables on Windows to specify the location of both OpenSSL DLLs:

- MITK_OPENSSL_SSL_DLL
- MITK_OPENSSL_CRYPTO_DLL

MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK,MITK/MITK