Update base.py

Correct more grammar.

couchpotato/core/plugins/base.py

@@ -145,7 +145,7 @@ class Plugin(object):
                 f.close()
                 os.chmod(path, Env.getPermission('file'))
             except:
-                log.error('Unable writing to file "%s": %s', (path, traceback.format_exc()))
+                log.error('Unable to write file "%s": %s', (path, traceback.format_exc()))
                 if os.path.isfile(path):
                     os.remove(path)