Disable extra_symbols for strict codecs
Create coding_technique template parameter in jerasure classes
Enable cauchy_orig and cauchy_good coding techniques in jerasure.cpp
Disable compiler flags for unsupported instruction sets on the current CPU

Note that Jerasure does not have any dynamic dispatch logic, so enabling all flags would lead to illegal instruction errors
Merge pull request #9 from steinwurf/add-cauchy

Add cauchy