Add ability to parse SIM Service Table (EF.SST)

As per TS.51.011, This EF indicates which services in the SIM are allocated, and whether, if allocated, the service is activated
.If a service is not indicated as available in the SIM, the ME shall not select this service.

Change-Id: Id28a35727adbaaa9df19b1adc621a0c51ad0e51b
diff --git a/pySim/cards.py b/pySim/cards.py
index d27092d..a12b111 100644
--- a/pySim/cards.py
+++ b/pySim/cards.py
@@ -188,7 +188,15 @@
 		else:
 			return (None, sw)
 
-	# Read the (full) AID for either ISIM or USIM application
+	# Read SIM Service table
+	def read_sst(self):
+		(res, sw) = self._scc.read_binary(EF['SST'])
+		if sw == '9000':
+			return ((res, parse_st(res)), sw)
+		else:
+			return (None, sw)
+
+	# Read the (full) AID for either ISIM or USIM or ISIM application
 	def read_aid(self, isim = False):
 
 		# First (known) halves of the AID