remember Me functionality should not be used with normal oauth flow

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@173271 a5903396-d722-0410-b921-86c7d4935375
Improving SAML2 Assertion Profile for OAuth 2.0 by retrieving certificate for assertion signature validation from KeyInfo elelment and checking for trust in keystore or if KeyInfo is not present taking all the certificates from key store. To improve performance a trustEntityId (alias) attribute can be specifed in the Issuer element in identity.xml to pick exactly one certificate only

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@173273 a5903396-d722-0410-b921-86c7d4935375