Fix: self.counters need to be initialized

When i use `--first`:

```
$python pep8.py --first testsuite/utf-8.py
testsuite/utf-8.py:43:80: E501 line too long (80 > 79 characters)
```
but when i check current directory:

```
$python pep8.py --first
...
./testsuite/E90.py:9:2: E901 IndentationError: unindent does not match any outer indentation level
./testsuite/W29.py:7:1: W293 blank line contains whitespace
./testsuite/W60.py:2:5: W601 .has_key() is deprecated, use 'in'
./testsuite/W60.py:5:17: W602 deprecated form of raising exception
./testsuite/W60.py:12:6: W603 '<>' is deprecated, use '!='
./testsuite/W60.py:15:7: W604 backticks are deprecated, use 'repr()'
```
the `testsuite/utf-8.py` is no displayed. i found the self.counters has not been initialized, `E501 `  has counted before