Refactor HMRC contacts show page and add more info for addresses

• refactor and a general tidy of code
• update css styles to adopt decent naming convention
• remove unecessary code, css, html, ruby and partials etc
• add 'more info for addresses'
Updates in response to pull request feedback

• remove used image
• move media mixin
• update font colour for variable
• update govspeak inside span
CSS structure updates

• removing measurements scss as it is not required
• updating percentage widths in dimensions files
• updating instances of 75% to variable
Doh, I deleted the wrong image, putting it back
Nothing to see here :-"
Render Govspeak with correct css

Adding the govspeak.scss file and wrapping govspeak in a div
Refactor SCSS to use frontend toolkit for measurements

As per https://github.com/alphagov/hmrc-contacts/commit/f186ee458e85acd84263680fe5d2df423ecdcf88
I'm using the frontend tookit and only keeping that around for
measurements. There's also a PR at https://github.com/alphagov/govuk_frontend_toolkit/pull/110
for adding 3/4 into the toolkit.
Merge pull request #124 from alphagov/refactor-contacts-show-page

https://www.pivotaltracker.com/s/projects/1010882/stories/68808102