Add BlockErupter Driver
limit minimum diff to 64
fix bug in setdiff
compatible with X24 board
Add option to set clock ('--bet-clk X' actual clock is (X+1)*10 )
Roll back to original .gitignore
Fix number of nos
Fix coding style
Merge remote-tracking branch 'upstream/master'
remove unnecessary sleep; fix potenital div by 0 errs; use min_diff in driver definition
Merge pull request #647 from blockerupter/master

Add driver for ASICMiner Tube/Prisma. Thanks very much.