Create a new core-layout layout

Create a new layout which provides the toolkit grid mixins as classes.
It also ensures the wrapper is the correct width. This can then be used
by new applications which want to use the new grid styles without having
to redefine the grid classes before the start.
Add some basic docs around the slimmer templates

So that people know what the templates are for and when you might use
them introduce some basic documentation describing when you might want
to use them.
Add basic reset to remove spacing and font-sizes

Remove extra padding and margin by default from all elements. This will
then let us explicitly add the whitespace that we want for each element.
Make strong bold
Merge pull request #483 from alphagov/column-layout

Create a new core-layout layout
Update SelectionButtons to new interface

Version 2.0.0 of the govuk_frontend_toolkit deprecated the old interface
to SelectionButtons. This now uses the new style.
Merge pull request #484 from alphagov/depricated

Update SelectionButtons to new interface
Bump govuk-template to 0.10.1

This version bump:
- Add 16x16 favicon for non-retina screens
- Force scrollbar to always display on IE10/11
- Release documents in gh-pages branch
- Fix chunky Firefox fonts
Merge pull request #485 from alphagov/bump-govuk-template

Bump govuk-template to 0.10.1