Now thros exception if no message recieved

Author: pjb304

plantower/plantower.py

@@ -133,3 +133,4 @@ def read(self, perform_flush=True):
                     self._verify(recv) # verify the checksum
                     return PlantowerReading(recv) # convert to reading object
             #If the character isn't what we are expecting loop until timeout
+        raise PlantowerException("No message recieved")

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="plantower",
-    version="0.0.2",
+    version="0.0.3",
     author="Philip Basford",
     author_email="[email protected]",
     description="An interface for plantower particulate matter sensors",