Paver: fail if pylint/pep8 violations threshold is breached.

Can we describe the various parts of this regular expression?
```python
pylint_pattern = re.compile(r"""
    .       # a random character
    (\d+)   # the line number number
    :[ ]    # a colon, followed by a space
    \[(\D\d+.+\])  # what is this?
    .      # another random character
""", re.VERBOSE)
```
I suspect that it may not work the way you think.