Use YAML for docs rather than JSON

YAML gives us the ability to have multi-line strings. JSON makes this
very hard.

Multi-line strings will be really useful to show fixtures when you are
passing around blocks of html.
Add govspeak component

Create a component for govspeak. All this will do is output the content
passed to it. By being a component it means that the styling can be
managed in a consistent place, so changes can be rolled out to all of
our text blocks in one go.

The Sass for this has mostly been lifted straight out of whitehall with
some minor alterations (things like using standard typography mixins
rather than whitehall specific ones).
Merge pull request #486 from alphagov/govspeak-component

Govspeak Component
Add title component

Add a component for page titles. The title should be large by default
with an option to make it smaller for longer titles.

On average the titles on government bits of content are twice as long as
those found on general guidance. We shrink the font size down so that
90% of titles will fit onto two lines.
Merge pull request #487 from alphagov/title-component

Add title component
Add document footer component

Add a component to show metadata about a document at the bottom of
the page.
Fix bad copy paste in docs
Pass optional message to Beta Banner

In certain instances, the default text for the Beta Banner doesn't work.
This commit adds the ability to pass the message in as a local to the
partial.
Merge pull request #489 from alphagov/pass-message-to-beta-banner

Pass optional message to Beta Banner
Explain that the Beta Banner can take HTML

With the option to add a different message for the Beta Banner the user
can pass in HTML. This commit explains in the Docs that passing HTML
in the message is possible.
Merge pull request #490 from alphagov/explain-html-in-beta-banner

Explain that the Beta Banner can take HTML
Merge pull request #488 from alphagov/document-footer

Add document footer component
Only display updated if it is non-falsy

Updated can be passed in as nil and in that situation we don't want to
display an empty updated.
Remove bullet from change-notes

The list doesn't want bullet points. This was being applied by other
Sass in the component guide. Add an explicit no list style.
Merge pull request #491 from alphagov/component-updates

Minor component updates
Enhance YouTube videos in govspeak content

Govspeak that contains links to youtube videos should be expanded into
an accessible video player. This adds the styles for the video player
and adds the JavaScript to identify the appropriate youtube links and
turn them into video players.

Moved the includes for jQueryUI and the player jQuery plugin into the
govspeak video component JavaScript file. This ensures that all the
dependencies are loaded.
Update Legislative List styles

(This work as requested by edds here: https://github.com/alphagov/manuals-frontend/pull/111)

Feedback from users of .legislative-list is that the list items sort of melt into one big blob of text. This occurs because of the (unusual but neccesary) way legislative-lists are implemented, which is that the author of the list puts the decorator in the list item. This is required because the lists are written in law (including the decorator) and then are not standardised.

This commit increases the indentation of nested ol's and adds more margin around individual list items to make them easier to read in the absence of proper text indenting which happens with regular lists.

Trello: https://trello.com/c/dhQk1nI5/420-manuals-additional-spacing-between-list-items-1
Merge pull request #493 from alphagov/update-legislative-lists

Update Legislative List styles
Merge pull request #492 from alphagov/youtube-videos

Enhance YouTube videos in govspeak content