cleaned up client crypto dependencies

added a new scrypt library that is about 3x faster as
emscrypt.js. It should be factored into its own module
on npm eventually.

also updated the npm sjcl dependency to 1.0.0 (official)
and removed the sjcl-codec-bytes dep by using hex instead.
Merge pull request #271 from dannycoates/emscrypt

cleaned up client crypto dependencies