DEV: move send => public_send in lib folder

This handles most of the cases in `lib` where we were using send instead
of public_send

lib/single_sign_on.rb

@@ -64,8 +64,6 @@ class SingleSignOn
     decoded = Base64.decode64(parsed["sso"])
     decoded_hash = Rack::Utils.parse_query(decoded)
 
-    return_sso_url = decoded_hash['return_sso_url']
-
     if sso.sign(parsed["sso"]) != parsed["sig"]
       diags = "\n\nsso: #{parsed["sso"]}\n\nsig: #{parsed["sig"]}\n\nexpected sig: #{sso.sign(parsed["sso"])}"
       if parsed["sso"] =~ /[^a-zA-Z0-9=\r\n\/+]/m
@@ -94,7 +92,7 @@ class SingleSignOn
   end
 
   def diagnostics
-    SingleSignOn::ACCESSORS.map { |a| "#{a}: #{send(a)}" }.join("\n")
+    SingleSignOn::ACCESSORS.map { |a| "#{a}: #{public_send(a)}" }.join("\n")
   end
 
   def sso_secret