Add RapidSSL intermediate CA

@mutemule /cc @Shopify/payments.

Netregistry is changing the URL for their gateway, but they are currently missing an intermediate when serving a chain. This is a workaround.

http://www.netregistry.com.au/support/payment-gateway-merchant-url-change-2014/

![image](https://cloud.githubusercontent.com/assets/426180/3618576/761dcc2a-0deb-11e4-8baa-e75c5b6469f7.png)

```
SHA1 Fingerprint=C0:39:A3:26:9E:E4:B8:E8:2D:00:C5:3F:A7:97:B5:A1:9E:83:6F:47
```
```
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 145105 (0x236d1)
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: C=US, O=GeoTrust Inc., CN=GeoTrust Global CA
        Validity
            Not Before: Feb 19 22:45:05 2010 GMT
            Not After : Feb 18 22:45:05 2020 GMT
        Subject: C=US, O=GeoTrust, Inc., CN=RapidSSL CA
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:c7:71:f8:56:c7:1e:d9:cc:b5:ad:f6:b4:97:a3:
                    fb:a1:e6:0b:50:5f:50:aa:3a:da:0f:fc:3d:29:24:
                    43:c6:10:29:c1:fc:55:40:72:ee:bd:ea:df:9f:b6:
                    41:f4:48:4b:c8:6e:fe:4f:57:12:8b:5b:fa:92:dd:
                    5e:e8:ad:f3:f0:1b:b1:7b:4d:fb:cf:fd:d1:e5:f8:
                    e3:dc:e7:f5:73:7f:df:01:49:cf:8c:56:c1:bd:37:
                    e3:5b:be:b5:4f:8b:8b:f0:da:4f:c7:e3:dd:55:47:
                    69:df:f2:5b:7b:07:4f:3d:e5:ac:21:c1:c8:1d:7a:
                    e8:e7:f6:0f:a1:aa:f5:6f:de:a8:65:4f:10:89:9c:
                    03:f3:89:7a:a5:5e:01:72:33:ed:a9:e9:5a:1e:79:
                    f3:87:c8:df:c8:c5:fc:37:c8:9a:9a:d7:b8:76:cc:
                    b0:3e:e7:fd:e6:54:ea:df:5f:52:41:78:59:57:ad:
                    f1:12:d6:7f:bc:d5:9f:70:d3:05:6c:fa:a3:7d:67:
                    58:dd:26:62:1d:31:92:0c:79:79:1c:8e:cf:ca:7b:
                    c1:66:af:a8:74:48:fb:8e:82:c2:9e:2c:99:5c:7b:
                    2d:5d:9b:bc:5b:57:9e:7c:3a:7a:13:ad:f2:a3:18:
                    5b:2b:59:0f:cd:5c:3a:eb:68:33:c6:28:1d:82:d1:
                    50:8b
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Key Usage: critical
                Certificate Sign, CRL Sign
            X509v3 Subject Key Identifier:
                6B:69:3D:6A:18:42:4A:DD:8F:02:65:39:FD:35:24:86:78:91:16:30
            X509v3 Authority Key Identifier:
                keyid:C0:7A:98:68:8D:89:FB:AB:05:64:0C:11:7D:AA:7D:65:B8:CA:CC:4E

            X509v3 Basic Constraints: critical
                CA:TRUE, pathlen:0
            X509v3 CRL Distribution Points:

                Full Name:
                  URI:http://crl.geotrust.com/crls/gtglobal.crl

            Authority Information Access:
                OCSP - URI:http://ocsp.geotrust.com

    Signature Algorithm: sha1WithRSAEncryption
         ab:bc:bc:0a:5d:18:94:e3:c1:b1:c3:a8:4c:55:d6:be:b4:98:
         f1:ee:3c:1c:cd:cf:f3:24:24:5c:96:03:27:58:fc:36:ae:a2:
         2f:8f:f1:fe:da:2b:02:c3:33:bd:c8:dd:48:22:2b:60:0f:a5:
         03:10:fd:77:f8:d0:ed:96:67:4f:fd:ea:47:20:70:54:dc:a9:
         0c:55:7e:e1:96:25:8a:d9:b5:da:57:4a:be:8d:8e:49:43:63:
         a5:6c:4e:27:87:25:eb:5b:6d:fe:a2:7f:38:28:e0:36:ab:ad:
         39:a5:a5:62:c4:b7:5c:58:2c:aa:5d:01:60:a6:62:67:a3:c0:
         c7:62:23:f4:e7:6c:46:ee:b5:d3:80:6a:22:13:d2:2d:3f:74:
         4f:ea:af:8c:5f:b4:38:9c:db:ae:ce:af:84:1e:a6:f6:34:51:
         59:79:d3:e3:75:dc:bc:d7:f3:73:df:92:ec:d2:20:59:6f:9c:
         fb:95:f8:92:76:18:0a:7c:0f:2c:a6:ca:de:8a:62:7b:d8:f3:
         ce:5f:68:bd:8f:3e:c1:74:bb:15:72:3a:16:83:a9:0b:e6:4d:
         99:9c:d8:57:ec:a8:01:51:c7:6f:57:34:5e:ab:4a:2c:42:f6:
         4f:1c:89:78:de:26:4e:f5:6f:93:4c:15:6b:27:56:4d:00:54:
         6c:7a:b7:b7
```