Adding updated touch icon sizes
New iOS 7 compatible sizes
Update apple touch icon sizes

Apple have updated the optimal sizes to serve precomposed icons as.
Update the references to the new icon sizes and delete the old ones.

The new sizes and documentation can be seen here:

https://developer.apple.com/library/ios/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/IconMatrix.html#//apple_ref/doc/uid/TP40006556-CH27
Merge pull request #86 from alphagov/updated-touch-icons

Adding updated touch icon sizes