Merge pull request bitcoin#1340 from hujiulong/patch-1

Add BIP39 implementation reference

Author: luke-jr

bip-0039.mediawiki

@@ -168,6 +168,7 @@ Haskell:
 JavaScript:
 * https://github.com/bitpay/bitcore/tree/master/packages/bitcore-mnemonic
 * https://github.com/bitcoinjs/bip39 (used by [[https://github.com/blockchain/My-Wallet-V3/blob/v3.8.0/src/hd-wallet.js#L121-L146|blockchain.info]])
+* https://github.com/hujiulong/web-bip39
 
 Java:
 * https://github.com/bitcoinj/bitcoinj/blob/master/core/src/main/java/org/bitcoinj/crypto/MnemonicCode.java