Fixed SANTUARIO-379: Signing XML with SHA1 with DSA throws exception when key is larger than 1024
Also added support for dsa-sha256 Signature Algorithm.


git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/branches/1.5.x-fixes@1592986 13f79535-47bb-0310-9956-ffa450edef68