Add JPY exchange rate (#4016)

lib/currencies.json

@@ -798,5 +798,14 @@
         "RUB",
         "USD"
     ],
-    "itBit": []
+     "itBit": [],
+     "Bitbank": [
+         "JPY"
+     ],
+     "BitFlyer": [
+         "JPY"
+     ],
+     "Zaif": [
+         "JPY"
+     ]
  }

lib/exchange_rate.py

@@ -160,6 +160,20 @@ class BitcoinVenezuela(ExchangeBase):
                              "/historical/index.php?coin=BTC")[ccy +'_BTC']
 
 
+class Bitbank(ExchangeBase):
+
+    def get_rates(self, ccy):
+        json = self.get_json('public.bitbank.cc', '/btc_jpy/ticker')
+        return {'JPY': Decimal(json['data']['last'])}
+
+
+class BitFlyer(ExchangeBase):
+
+    def get_rates(self, ccy):
+        json = self.get_json('bitflyer.jp', '/api/echo/price')
+        return {'JPY': Decimal(json['mid'])}
+
+
 class Bitmarket(ExchangeBase):
 
     def get_rates(self, ccy):
@@ -350,6 +364,12 @@ class Winkdex(ExchangeBase):
                      for h in history])
 
 
+class Zaif(ExchangeBase):
+    def get_rates(self, ccy):
+        json = self.get_json('api.zaif.jp', '/api/1/last_price/btc_jpy')
+        return {'JPY': Decimal(json['last_price'])}
+
+
 def dictinvert(d):
     inv = {}
     for k, vlist in d.items():