removed obsolete crypto functions

package.json

@@ -10,8 +10,6 @@
   },
   "dependencies": {
     "debounce": "^1.0.0",
-    "elliptic": "^6.3.2",
-    "js-sha3": "^0.5.7",
     "react": "^15.4.2",
     "react-native": "0.40.0",
     "react-native-camera": "^0.5.1",

src/util/crypto.js

-import { ec } from 'elliptic'
-import { keccak_256 } from 'js-sha3'
-var secp = new ec('secp256k1')
 import { EthkeyBridge } from 'NativeModules'
 
-export function keypairFromPhrase(phrase) {
-  var seed = keccak_256.array(phrase);
-  var kp;
-  for (var i = 0; i <= 16384 || !toAddress(kp = secp.keyFromPrivate(seed)).startsWith('00'); ++i)
-    seed = keccak_256.array(seed)
-  return kp
-}
-
-export function toAddress(kp) { return keccak_256(kp.getPublic('buffer').slice(1)).substr(24); }
-
-export function brainWalletAddress(seed, callback) {
-  EthkeyBridge.brainWalletAddress(seed, callback)
-}
+export const brainWalletAddress = EthkeyBridge.brainWalletAddress;
+export const brainWalletSecret = EthkeyBridge.brainWalletSecret;