filesystem: fix reset mechanism

Currently we call the reset_card and get_atr methods directly at the
transport layer via the private _scc and _tp object of the card. This is
a violation. Fix and use the reset methods that are already in the
SimCard object.

Change-Id: I0e9d2a62a42a7387e7ca69d2ae830782a61aed89

pySim/cards.py

@@ -60,7 +60,11 @@ class SimCard(object):
 		self._aids = []
 
 	def reset(self):
-		self._scc.reset_card()
+		rc = self._scc.reset_card()
+		if rc is 1:
+			return self._scc.get_atr()
+		else:
+			return None
 
 	def erase(self):
 		print("warning: erasing is not supported for specified card type!")