Add dev dependency on seq package

This package is built in to Emacs 25 but not Emacs 24.

Cask

@@ -1,9 +1,11 @@
 ;; -*- mode: emacs-lisp -*-
 
+(source gnu)
 (source melpa)
 
 (package "ido-ubiquitous" "4.0" "Use ido (nearly) everywhere.")
 
 (development
  (depends-on "f")
+ (depends-on "seq")
  (depends-on "ert-runner"))

test/ido-cr+-test.el

@@ -3,6 +3,7 @@
 (require 'ido-completing-read+)
 (require 'ert)
 (require 'cl-lib)
+(require 'seq)
 
 ;; This is a series of macros to facilitate the non-interactive
 ;; testing of interactive functions by simulating user input.