message: Use KeyFormat instead of hard-coded string.
diff: const MslCryptoException = require('../MslCryptoException.js');
  const MslError = require('../MslError.js');
  const MslCrypto = require('../crypto/MslCrypto.js');
  + const KeyFormat = require('../crypto/KeyFormat.js');
  const Base64 = require('../util/Base64.js');
  var SecretKey = module.exports = Class.create({
  var onerror = function(e) {
  callback.error(new MslCryptoException(MslError.INVALID_SYMMETRIC_KEY, null, e));
  };
  - MslCrypto.importKey("raw", keydata, algo, true, usages)
  + MslCrypto.importKey(KeyFormat.RAW, keydata, algo, true, usages)
  .then(oncomplete, onerror);
  });
  };
  