Use base ruby image in Dockerfile & fix watcher

It seems that the watcher will not work without the
--force-polling option.

upgraded to wily to remove error from version trusty

Basic Vagrant support. Close #348

More memory needed for `rake publish`

Need git for `rake publish`

Add hosting.de API docs to the list

make middleman pick up changes when run in docker

Add SafetyCulture API to the list

Fix Dockerfile by installing nodejs

Add SocialRadar to the list of docs sites using Slate

Use HTTPS for github urls.

Update gems

Remove therubyracer in favor of system JS runtimes

adding supporkit docs as an example

Add Aircall.io to README

Improved the appearance of code blocks when printing.

Slate 1.2.1
@lord my fault, I seemed to have totally missed the emails sent!

Add OAuth.io to README