Allow ignore_decorators to pass to pydocstyle.

[GrandVizierOlaf]

This will pass parameters to pydocstyle, retrieve ignore_decorators if it exists, and then use it.

There was also a bug with ini_path always having been stringified in my testing, so that is also checked now.

[coveralls]

Coverage remained the same at 77.445% when pulling 3b83a60 on GrandVizierOlaf:develop into 8daaa42 on klen:develop.

[GrandVizierOlaf]

This is meant to fix #106.

[klen]

@GrandVizierOlaf Thank you!