Merge pull request #125 from alphagov/add-conditional-for-summary

Wrap the @manual.summary in a conditional
Whitespace fixes to index view
Make the list an ol not ul

I think this list of index items is probably an ordered list not an un-ordered list. Based on the fact that arbitrarily switching two items in the list would result in a less meaningful order.
Small fix to index.html.erb

Switch from unless .blank? to if ... .present? as it's an easier to understand way to express the same thing.