Timestamp issues #7

The thing is that if frasec: resolves as False if frasec is zero.

We will fix this issue by checking if frasec is not None: (and if soc is not None:).
Methods set_soc() and set_frasec() will validate values.

synchrophasor/frame.py

@@ -226,12 +226,12 @@ def set_time(self, soc=None, frasec=None):
 
         t = time()  # Get current timestamp
 
-        if soc:
+         if soc is not None:
             self.set_soc(soc)
         else:
             self.set_soc(int(t))  # Get current timestamp
 
-        if frasec:
+        if frasec is not None:
             if isinstance(frasec, collections.Sequence):
                 self.set_frasec(*frasec)
             else: