OSX El Capitan need brew link openssl -force

We got the following note added to the WSO wiki from @freeranger (I think) following our install instructions:

> **Note:** On OSX El Capitan and above, you may get this error:
>
> ```
> An error occurred while installing eventmachine (1.0.7), and Bundler cannot continue.
> Make sure that `gem install eventmachine -v '1.0.7'` succeeds before bundling.
> ```
>
> If you then try to install that gem, it also fails like this: https://github.com/eventmachine/eventmachine/issues/643, which is because OpenSSL is no longer distributed with OSX so you may need to use brew to set it up:
>
> ```
> brew link openssl --force
> ```
>
> Then re-try the rails_setup.sh line above and you should be good to go on to the next step.

Assuming that we think that maintaining this script is something that makes sense for us then perhaps we should update and fix this issue in the setup script itself ...

Perhaps we should be recommending people to use [C9](c9.io) - @dalupus - I wonder if this script (with some fixes) set to autorun when someone created a c9 instance would be what we want in terms of a C9 "template" https://github.com/AgileVentures/WebsiteOne/issues/807