Add root namespace prefix
Add input style to text area elements too

Also added example to `inputs.html.erb`.
Add placeholder mixin
Tidy up input styling
Rename functions dir to mixins
Revert "Update to latest middleman"

This reverts commit 871a80c77c9181bb73e262ce78b402c8425cbcaa.
Whitespace
Update form styles and separate SCSS into more files and structure form specific styles under modules/forms
Whitespace
Remove change in font for forms
Improve form spacing and bring HTML inline with simple forms
Improve button spacing and include example in inputs.html.erb
Improve positioning of radio/checkbox selected icons
Improve label spacing for checkbox/radio
Update hr spacing to use margin-top only
Add disabled input style
Tidy up input container and title HTML
Update typography to match semantics with sizes

It seemed strange h2 in most cases was bigger than h1.
Move select2 style from vendor into app since it's custom SCSS and not as provided by vendor
Tidy up structure of SCSS