Added SAML2 support (#185)

* ~ in gitignore

* add config options for SAML authentication

* add information about SP metadata

* add gem for omniauth-saml

* Add the SAML strategy as a middleware

* add gem for omniauth-saml

* Send SAML request to saml module

* Pass env parameters to saml provider

* Add options for specifying saml signing certificate

* Almost there

* Re-enable SAML redirection

* Correctly map saml attributes

* change full certificate to only the fingerprint

* change full certificate to only the fingerprint

* revert changes to gitgnore

* cleanup

Gemfile.lock

@@ -163,6 +163,9 @@ GEM
     omniauth-oauth2 (1.5.0)
       oauth2 (~> 1.1)
       omniauth (~> 1.2)
+    omniauth-saml (1.8.1)
+      omniauth (~> 1.3)
+      ruby-saml (~> 1.4, >= 1.4.3)
     omniauth-twitter (1.2.1)
       json (~> 1.3)
       omniauth-oauth (~> 1.1)
@@ -213,6 +216,8 @@ GEM
       ffi (>= 0.5.0, < 2)
     request_store (1.4.0)
       rack (>= 1.4)
+    ruby-saml (1.4.3)
+      nokogiri (>= 1.5.10)
     rubyntlm (0.3.4)
     sass (3.5.5)
       sass-listen (~> 4.0.0)
@@ -302,6 +307,7 @@ DEPENDENCIES
   omniauth (= 1.6.1)
   omniauth-google-oauth2 (= 0.4.1)
   omniauth-ldap
+  omniauth-saml
   omniauth-twitter (= 1.2.1)
   paperclip (~> 5.1)
   pg