antminer: Initial support for the Bitmain AntMiner U1 ASIC
Includes support for identifying the U1 separately from Icarus and Block Erupter
Also includes overclocking via --set-device antminer:clock=xHEX
Merge pull request #373 from nwoolls/feature/antminer-u1-support

antminer: Initial support for the Bitmain AntMiner U1 ASIC