Changes the way the SAML metadata are generated

- Fixes the attributed for the signing cert
- Adds proper encoding
- Changes the way the XML is build in order to add nodes in a more
  flexible way
Merge pull request #58 from skanct/enhance_saml_metadata_generation

Changes the way the SAML metadata are generated
- update login page
Merge pull request #59 from cmarinos/master

- update login page