Improve transaction overview for non high street purchases

[robcalcroft]

Things bought online or through PayPal often have a rather ugly overview as there is not much info to show. Make the Overview component more robust in dealing with this and attempt to further hide locations if they are not relevant etc.

Potentially replace the fallback icon.

[robcalcroft]

@zaccolley how do you think is best to deal with the lack of map for transactions like these as currently we just have a grey box, could do with either hiding the box or showing something in the box like 'No location available'?

[robcalcroft]