add Bitso exchange rate

plugins/exchange_rate/exchange_rate.py

@@ -22,7 +22,7 @@ CCY_PRECISIONS = {'BHD': 3, 'BIF': 0, 'BYR': 0, 'CLF': 4, 'CLP': 0,
                   'LYD': 3, 'MGA': 1, 'MRO': 1, 'OMR': 3, 'PYG': 0,
                   'RWF': 0, 'TND': 3, 'UGX': 0, 'UYI': 0, 'VND': 0,
                   'VUV': 0, 'XAF': 0, 'XAG': 2, 'XAU': 4, 'XOF': 0,
-                  'XPF': 0}
+                  'XPF': 0, 'MXN': 2}
 
 class ExchangeBase(PrintError):
 
@@ -131,6 +131,14 @@ class BTCParalelo(ExchangeBase):
     def protocol(self):
         return "http"
 
+class Bitso(ExchangeBase):
+    def get_rates(self, ccy):
+        json = self.get_json('api.bitso.com', '/v2/ticker')
+        return {'MXN': Decimal(json['last'])}
+
+    def protocol(self):
+        return "http"
+
 class Bitcurex(ExchangeBase):
     def get_rates(self, ccy):
         json = self.get_json('pln.bitcurex.com', '/data/ticker.json')