Added support for reading epub files directly from a java.zip.ZipFile instead of a ZipInputStream:
the ZipInputStream approach stops reading from the input when a null entry is found, which in some cases leads to a toc-not-found-error.

Conflicts:

	epublib-core/src/main/java/nl/siegmann/epublib/domain/Resource.java
Merge pull request #51 from NightWhistler/patch_on_patch

Cleaned up original patch so it no longer requires Apache IOUtils