commands: add method to determine size of a non record oriented file

For record oriented files we have the methods record_size() and
record_count() to determine the dimensions of a record oriented file,
however, we miss a similar function for regular binary files. Lets add a
method binary_size() to quickly determine the size of a non record
oriented file

Change-Id: I0593f2de7f34d5654a19e949dc567a236e44e20c

pySim/commands.py

@@ -152,6 +152,10 @@ class SimCardCommands(object):
 		r = self.select_file(ef)
 		return self.__len(r) // self.__record_len(r)
 
+	def binary_size(self, ef):
+		r = self.select_file(ef)
+		return self.__len(r)
+
 	def run_gsm(self, rand):
 		if len(rand) != 32:
 			raise ValueError('Invalid rand')