fix pylintrc to run with pylint/python 3

Current pylintrc will cause an error in pylint, if invoked with python 3:

```
configparser.DuplicateSectionError: While reading from '/home/felix/projects/boto/pylintrc' [line 304]: section 'MESSAGES CONTROL' already exists
```

Merging the section solves this easily.
Ah, you are right. I just did a simple test and the second section does indeed overwrite the first. Your change looks good, sorry about that!