Bugfix: Make dpkg-source ignore .git in more cases

In some cases the '-I' param to dpkg-source is not enough. In this case
builds fail since dpkg-source complains about modified files.
This additionally adds (previously used) '-i' to the params, which
fixes those cases.
Merge pull request #52 from credativ/bugfix/dpkg-source-not-ignoring-git

Bugfix: Make dpkg-source ignore .git in more cases