Added up-to-date build and usage instructions to README.
Added up-to-date build and usage instructions to README.

surround-io/oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,mpflanzer/Oclgrind,surround-io/oclgrind,surround-io/oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind