rspec/rspec-core — pull request #1245 by walf443 (2014-01-13 23:33:14+00:00)
Title: fixed warnings from ruby 2.1.0

some warnings occured from ruby 2.1.0 or later. This patch fix this problem.

warnings are followings:

```
warning: File.exists? is a deprecated name, use File.exist? instead
```