Normally, one would add libraries and python modules to a bundle using LD_LIBRARY_PATH
and PYTHONPATH.  This gives them priority over the systemwide versions of these items.
However, this is a dangerous approach, as if the included versions are incompatible with
the system, the program will not run.  ldshim.py creates a safer alternative, by adding
the bundled binaries to the _end_ of the search path, rather than the beginning, so that
systemwide binaries take precedence.

To produce a bundle from RPMs, one must download them into the bundle path
and then execute

cat [name].rpm | rpm2cpio | cpio -di

for each RPM.  This will produce a new root directory tree based on the
current path.  One may also need to add other binaries to the tree manually
in directories like usr/bin/.

If adding python modules, it is important to ensure that every directory
recursively containing the python module is world-readable and executable.