Fixes dynamic NS bug in InclusiveNamespaces element query

extracts logic into a separate, private method. this allows us to test
the method in an isolated fashion and also shortens the lenght of the #validate_doc
method ( a little too long IMO ).
Fixes bug with SignedDocument#validate_doc

calling this method more than once would result in an exception being
thrown because the signature node is removed from the root document in the first
invocation.

this node is being stored in an attr_accessor because subsequent calls to
the #validate_doc method need it to function properly.
Updates Response#issuer

The `<Issuer>` node can be located inside either the `<Response>` node or the `<Response><Assertion>`.
this change checks it in both places and lends preference to the former.
Extracted creation of the SAML authentication request into its own method, which can be called separately for use with a binding other than the HTTP Redirect one.
Updated .gitignore to ignore some intellij files.
Updated to remove time-zone component from the IssueInstant time (this is to conform with SAMLCore-2.0, section 1.3.3).
Added SAML 2.0 sctructure validation against Oasis Protocol Schema
Added SAML 20 & Digital Signature schemas
success? method and test
added success to validate method
Merge pull request #46 from luisvm/master

Validation against SAML 2.0 Protocol Schema
Merge pull request #47 from ghalley/success

Success method
Merge pull request #45 from zoodor/master

Extract authentication request code to separate method
Merge pull request #41 from drywheattoast/response_issuer

Updates Response#issuer
Merge pull request #39 from drywheattoast/error_on_multiple_validations

Fixes bug with SignedDocument#validate_doc
Merge pull request #38 from drywheattoast/inclusive_namespaces_query

Fixes dynamic NS bug in InclusiveNamespaces element query
Add support for canonicalization-algorithm detection
Pending test for canonicalization
Added settings for single log out (SLO) and convenience initializer.
Implemented single logout support.