Added SSL support for server connections

To enable SSL support you just need a `mysql_ssl` data bag with a `files` data bag item. This should contain the following three things.

1. CA Certificate
2. Certificate
3. Key

Example, in data_bags/mysql_ssl/files.json:

```json
{
    "id": "files",
    "ssl-ca": "-----BEGIN CERTIFICATE-----\n...\n-----END CERTIFICATE-----",
    "ssl-cert": "-----BEGIN CERTIFICATE-----\n...\n-----END CERTIFICATE-----",
    "ssl-key": "-----BEGIN RSA PRIVATE KEY-----\n...\n-----END RSA PRIVATE KEY-----"
}