Output career length using helper

Fixes #10
Remove handmade touch icons and favicon
Add 144x144 favicon base image
Add ImageMagick to provision script
Add middleman-favicon-maker to Gemfile
Call favicon_maker from config.rb
Update layout to match new touch icon and favicon specs
Add bundle command to fabfile
Update Gemfile
Merge branch 'feature/favicon_maker' into develop

Fixes #11
Extend date for Waitrose project
Demote Best Buy
Describe HSBC project
Update Home Office project description
Expand CIPFA description
Exclude generated versions in robots.txt

Fixes #13
Retire Suburb ops from featured projects
Add Waitrose project details
Expand client titles
Add Waitrose link