[Bugfix] Fix basic auth in deployed apps (#52)

* Renamed auth env vars and updated them to work in prod env

* Updated basic auth parsing to ignore empty strings

lib/pinchflat_web/router.ex

@@ -54,10 +54,14 @@ defmodule PinchflatWeb.Router do
     username = Application.get_env(:pinchflat, :basic_auth_username)
     password = Application.get_env(:pinchflat, :basic_auth_password)
 
-    if username && password do
+    if credential_set?(username) && credential_set?(password) do
       Plug.BasicAuth.basic_auth(conn, username: username, password: password, realm: "Pinchflat")
     else
       conn
     end
   end
+
+  defp credential_set?(credential) do
+    credential && credential != ""
+  end
 end