Add openssl to Requires

I think that openssl is required for installing rpm.

```
[root@localhost ~]# rpm -ivh /vagrant/ruby-2.1.1-1.el6.x86_64.rpm
error: Failed dependencies:
	libcrypto.so.10(OPENSSL_1.0.1_EC)(64bit) is needed by ruby-2.1.1-1.el6.x86_64
	libcrypto.so.10(libcrypto.so.10)(64bit) is needed by ruby-2.1.1-1.el6.x86_64
	libssl.so.10(libssl.so.10)(64bit) is needed by ruby-2.1.1-1.el6.x86_64
[root@localhost ~]# yum -y install openssl
[root@localhost ~]# rpm -ivh /vagrant/ruby-2.1.1-1.el6.x86_64.rpm
Preparing...                ########################################### [100%]
   1:ruby                   ########################################### [100%]
[root@localhost ~]# ruby -v
ruby 2.1.1p76 (2014-02-24 revision 45161) [x86_64-linux-gnu]
```