Fix error reporting when phantomjs doesn't start

You can't pass the exception to `raise` as an argument, you need to to explicitly include it in the string.

Signed-off-by: Luke Inman-Semerau <[email protected]>

Author: dsem

Diff for: py/selenium/webdriver/phantomjs/service.py

@@ -75,7 +75,7 @@ def start(self):
                                             stdout=self._log, stderr=self._log)
 
         except Exception as e:
-            raise WebDriverException("Unable to start phantomjs with ghostdriver.", e)
+            raise WebDriverException("Unable to start phantomjs with ghostdriver: %s" % e)
         count = 0
         while not utils.is_connectable(self.port):
             count += 1