Merge pull request #233 from jamiehannaford/gh-pages

[wip] New content for gophercloud.io
Reference the logo from public/.
Merge pull request #268 from smashwilson/header-image

Reference the logo from public/.
Link to master's CONTRIBUTING.md.
Merge pull request #269 from smashwilson/contributing-link

Link to master's CONTRIBUTING.md.
utils.AuthOpts is no more.
Merge pull request #270 from smashwilson/fix-getting-started

utils.AuthOpts is no more.
Changing to kramdown because we get to have tabs
Removing spaces in favour of tabs
Ordering sidebar links alphabetically
Adding provider links to DRC