Removing the location icon from postcode forms

example - https://www.gov.uk/recycling-collections

This layout is broken on mobile and after discussing with designers
it was agreed that this icon is superfluous. So I've removed it
and the images.

https://www.pivotaltracker.com/story/show/73192808
Merge pull request #434 from alphagov/remove-postcode-form-icon

Removing the location icon from postcode forms