Generate default configs even if .codeclimate.yml already present
Generate default configs even if .codeclimate.yml already present

Currently, running codeclimate init with .codeclimate.yml present results in an
error message, and exit code 1..

Since it might still be useful for users to get default configs by running
`codeclimate init`, this change generates applicable configs even when
.codeclimate.yml present, before finishing with the same warning message and
exit code 1:

```
$ codeclimate init
Config file .csslintrc successfully generated.
Skipping generating coffeelint.json file (already exists).
Config file .eslintrc successfully generated.
Skipping generating .rubocop.yml file (already exists).
Config file .codeclimate.yml already present.
Try running 'validate-config' to check configuration.
```

codeclimate/codeclimate,mrb/codeclimate,codeclimate/codeclimate,mrb/codeclimate,mrb/codeclimate,codeclimate/codeclimate