prepend instead of appending to sys.path.

The rationale is that planet/vendor contains overrides of whatever the user has
in her local python install.

planet/__init__.py

@@ -32,7 +32,7 @@ def getLogger(level, format):
     loggerParms = (level,format)
     return logger
 
-sys.path.append(os.path.join(os.path.dirname(__file__),'vendor'))
+sys.path.insert(0, os.path.join(os.path.dirname(__file__),'vendor'))
 
 # Configure feed parser
 import feedparser