Terminate SSL at the load balancer

Implement SSL termination at the load balancer. Because the `rax_clb` module doesn't currently support HTTPS redirection or SSL termination, we'll need to override it with a local module and implement it there.

### Remaining Work

* [x] Acquire the SSL certificate for the prod CLB.
* [x] Create an SSL certificate for the staging CLB.
* [x] Create an enhanced version of the `rax_clb` Ansible module in `script/modules`. This module will add functionality for applying SSL certificates to CLBs to the `rax_clb` module and enabling HTTPS redirection. See http://docs.rackspace.com/sdks/api/python/classpyrax_1_1cloudloadbalancers_1_1CloudLoadBalancerManager.html#a66334c0c0a712389d1c0a3d1e43cbf98 and http://docs.rackspace.com/sdks/api/python/classpyrax_1_1cloudloadbalancers_1_1CloudLoadBalancerManager.html#aad4c90f91195d71b1d99ee598220cb14 on how to do this in pyrax. Note that this will need to be an idempotent operation.
* [x] Submit a PR against the upstream Ansible module.
* [x] Modify `deploy/prod_web.yml` and `deploy/staging_web.yml` to apply self-signed SSL certificates to CLBs.
* [x] Change monitoring checks to test for the 80 to 443 redirect and to verify that the certificate is up to date.
* [x] Load external JavaScript dependencies and Google Fonts from https sources.
* [x] Check for certificates in `deploy/certificates` in `script/deploy`.

Fixes #306.
Should this be `add_ssl_termination` or `update_ssl_termination` (per http://docs.rackspace.com/sdks/api/python/classpyrax_1_1cloudloadbalancers_1_1CloudLoadBalancerManager.html#aad4c90f91195d71b1d99ee598220cb14)?