Change intro test on oxfordshire cobrand

For #502
Increase default map zoom for oxfordshire cobrand

For #502
Remove whitespace
Specify width/height units in position_map
Explain what position_map_box is doing
Make the oxfordshire map wrapper full width
Fix spacing around content on oxfordshire map
Add the box shadow back to the map content box
Fix left margin of map at smaller breakpoint for oxfordshire
Don't specify units in css for 0
Enforce a min-height on the container for oxfordshire map
Make sure the map is draggable
Don't put the text in the document flow
Don't change the offset for the oxford co-brand
Don't rely on the url to determine the cobrand
Fix positioning of the sidebar
Reduce the width of the sidebar
Change the text for oxfordshire's big green banner
Styles for the big green banner on oxfordshire
Add extra text to the oxfordshire map page