Fix to check for zero s value in sign function

If r OR s are zero then recalculate both r and s until they are both non-zero values.
add ECIES support in node - not browser
use SJCL AES to get ECIES working in the browser
replace jssha with sjcl - remove jssha dependency
remove underscore dependency to decrease bundle size
remove unused commander dependency
add test to confirm correctness of sha512hmac
Merge pull request #357 from ionux/master

Fix to check for zero s value in sign function
add coveralls
add badge
rename "rand" to more explanatory "getRandomSeed"
Merge pull request #369 from maraoz/add/coveralls

add coveralls
Merge pull request #362 from ryanxcharles/feature/ECIES

add ECIES support