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