Make SSL verification on Mac OS X work out of the box

In `module_utils/urls.py` we build a temp file with ca certs discovered from common locations.  On OS X, there is no ca bundle file provided by default.

A bit of reading let me to http://mercurial.selenic.com/wiki/CACertificates#Mac_OS_X_10.6_and_higher which mentions, that if you have at least 1 cert, python on OS X will utilize OpenSSL which has hooks into keychain where the SSL certificates live on OS X.

I've generated a dummy cert per those instructions and included it in `urls.py`.  It will always be the first cert in the list, and on OS X will be the only cert in that file.

Here are the tests that I ran (stripped of a little bit of data):

### Current

```
$ ansible --version
ansible 1.6 (devel 750d9e2d59) last updated 2014/03/18 09:36:42 (GMT -500)

$ /test-module -m ../library/network/get_url -a 'url=https://cacert.org/ dest=/tmp/fail'

***********************************
RAW OUTPUT
{"msg": "Failed to validate the SSL certificate for cacert.org:443. Use validate_certs=no or make sure your managed systems have a valid CA certificate installed. Paths checked for this platform: /etc/ssl/certs, /etc/ansible", "failed": true}

$ ./test-module -m ../library/network/get_url -a 'url=https://ansible.com/ dest=/tmp/success'

***********************************
RAW OUTPUT
{"msg": "Failed to validate the SSL certificate for ansible.com:443. Use validate_certs=no or make sure your managed systems have a valid CA certificate installed. Paths checked for this platform: /etc/ssl/certs, /etc/ansible", "failed": true}
```

### After

```
$ ansible --version
ansible 1.6 (ssl-cert-validation-osx 3b5aa8bd30) last updated 2014/03/18 17:16:44 (GMT -500)

$ ./test-module -m ../library/network/get_url -a 'url=https://cacert.org/ dest=/tmp/fail'

***********************************
RAW OUTPUT
{"msg": "Failed to validate the SSL certificate for cacert.org:443. Use validate_certs=no or make sure your managed systems have a valid CA certificate installed. Paths checked for this platform: /etc/ssl/certs, /etc/ansible", "failed": true}

$ ./test-module -m ../library/network/get_url -a 'url=https://ansible.com/ dest=/tmp/success'

***********************************
RAW OUTPUT
{"src": "/var/folders/p3/b_15nft95md8kpmv32twplhr0000gn/T/tmpDqPZds", "changed": true, "group": "wheel", "uid": 501, "url": "https://ansible.com/", "md5sum": "c99593df81253a41ba279861b3ec6aea", "owner": "matt", "sha256sum": "", "dest": "/tmp/success", "state": "file", "gid": 0, "mode": "0644", "msg": "OK (unknown bytes)", "size": 57523}
```

I did test with other modules as well, such as the `nexmo` module which worked equally well.

For anyone interested here is the data used to generate the dummy cert:

Organization: Ansible
Locality: Durham
State: North Carolina
Country: US
Valid From: March 18, 2014
Valid To: March 15, 2024
Issuer: Ansible
Key Size: 1024 bit
Serial Number: ef04d764bbfea129