Show calorie and CO2 output calculations of a planned route

[mvl22]

Calculations of calorie usage and CO2 equivalent are now available in the API output.

http://www.cyclestreets.net/blog/2011/06/30/calories-burned-and-co2-saved/

http://www.cyclestreets.net/api/#jpReturnRoute

Presumably this would be a fairly simple thing to add as text somewhere. So it would be good to add these in, and provide an additional hook for promoting the app.

[mvl22]

CO2 saving: <grammesCO2saved (int)> Calories: <calories (int)>

NB the 2 in CO2 is usually written as small text lower on the line, i.e. CO₂, but this is not essential if it's hard to do.

[jezhiggins]

Extended API wrapper to grab co2 and calories. Added as extra information on the itinerary view header.