Removed devBlocks param
Validate no of threads for power of 2
Change kernel function to work on more than 1 element
take code out of if block
Time stuff (achim?) + take any file size

Sorry for the big commit.

Works on any file size now. Takes only threads arg and then calculates
the no. of blocks. Tries for the maximum no. of blocks possible. When
limit is reached each kernel function will process more elements.