Handle casing in directory names

This removes the need for a bundle file to exactly match the casing of
the directory on disk.
Throw if no files found

The most likely reason for this is a typo in the bundle file.  This
throws so that it is much more explicit.
Merge pull request #16 from Andrew-Hagedorn-ZocDoc/HandingCasingInDirectoryNames

Handing casing in directory names