Hi

* I made some change to have a more powerful ignore_filter https://github.com/jeremiejig/etckeeper/commit/faed9ba87a71a2d09cf078c0154bd3a6bd36786a
The filtering process concern only **git**.

* And I filter the empty directories to avoid creating ignored empty directories https://github.com/jeremiejig/etckeeper/commit/4f257707ed85097a93289b4a33f18ea21dcf3a6e

Tell me what you think.
