Revert "Add JPY exchange rate"

This reverts commit c2da8eb46d.

lib/currencies.json

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

lib/exchange_rate.py

@@ -159,19 +159,6 @@ class BitcoinVenezuela(ExchangeBase):
         return self.get_json('api.bitcoinvenezuela.com',
                              "/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):
 
@@ -363,12 +350,6 @@ 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():