Making a universal USB charger
Am I missing something here, but if you've got a power supply (assuming it's voltage regulated) that produces 5 volts at up to 2 Amps, all you do is cable up a USB connector don't you?  Then connect the USB connector into a USB charge cable with a micro USB connector on the other end and plug into the device you want to charge. The mobile phone or gadget will take whatever current it needs up to the maximumm of 2 amps. 

Is this question actually more complicated than that?  Whilst different phones may have different charging algorithms to suit their particular batteries, don't they all just take in a nice steady 5V DC input as their charging source?