fix pylint messages when pythonrc specifies format=colorized

Currently if a pylintrc specifies format=coloized, you end up with terminal escape codes in the locatiionlist.

Specifying --format=text fixes this, even though it doesn't change the actual format due to --msg-template.

The default pylintrc (from pylint --generate-rcfile) has output-format set to 'text' and details the possible values users can change it to. The obvious intent is to allow people to set it in pylintrc.

```
$ pylint --generate-rcfile | grep format
No config file found, using default configuration
# Set the output format. Available formats are text, parseable, colorized, msvs
output-format=text
I will change my patch to use the default format (text) rather than 'parseable'.
```

Due to your very recent patch, without this fix, format=colorized prevents syntastic+pylint from functioning at all.