Comply with phoenix 1.4 requirements of :url

Author: Samuel Lissner

lib/mix/tasks/swagger.generate.ex

@@ -180,7 +180,7 @@ defmodule Mix.Tasks.Phx.Swagger.Generate do
     url = Keyword.get(endpoint_config, :url)
     host = Keyword.get(url, :host, "localhost")
     port = Keyword.get(url, :port, 4000)
-    scheme = Keyword.get(url, :scheme, :http)
+    scheme = Keyword.get(url, :scheme, "http")
 
     swagger_map =
       if (!load_from_system_env) and is_binary(host) and (is_integer(port) or is_binary(port)) do
@@ -190,7 +190,7 @@ defmodule Mix.Tasks.Phx.Swagger.Generate do
       end
 
     swagger_map =
-      if scheme == :https do
+      if scheme == "https" do
         Map.put_new(swagger_map, :schemes, ["https", "http"])
       else
         swagger_map