ClassCastException still happen deep within BC - turn them into SignatureExeption

this happens when the signature is DSA but the public key for verification is RSA.

Sponsored by Lookout Inc.

Author: mkristian

src/main/java/org/jruby/ext/openssl/SecurityHelper.java

@@ -602,6 +602,10 @@ static boolean verify(final X509CRL crl, final PublicKey publicKey, final boolea
             catch (CertException e) {
                 throw new SignatureException(e);
             }
+	    // can happen if the input is DER but does not match expected strucure
+            catch (ClassCastException e) {
+                throw new SignatureException(e);
+            }
             catch (IOException e) {
                 throw new SignatureException(e);
             }