Update README.md
Merge pull request #114 from PartTimeLegend/patch-2

Update README.md
0.4.0 release | Fixed security hole | Fixed MHz bug | Recoded Mobileminer actions | Improved security hashing web password | Added Coinbase donation buttons | Ability to add custom miners | Skin selection (black/blue) | Minor fixes
README merged
Added missing screens
Rollback Bfgminer 4.8
Added libusb src
Renamed libusb src
Added libusb install from upgrade script
Bfgminer 5.0.0