Changed materials to match xsdrn

Changed the materials to mostly match the xsdrn calculation, while
increased the run length and the number of source particles to try an
get a better convergence.
Added MCNPX Run script

Added the MCNPX run script to submit jobs to the cluster.
Script to extract the results

Script to extract the MCNPX results.  This can be expanded to extract
the XSDRN k-effectives as well.
Added a white BC

Added a white BC instead of the reflective BC.  This is signified by a +
sign in front of the surface instead of a *.
Fixed error in prepend

Fixed in error in the prepend for the out, where I am trying to
automatically delete the output if it exists in the folder.
Removed print statements
Finally got prepend to work
Updated mcnp and added reference

Updated the MCNPX simulations to have a reflective boundary condition
and to use zircaloy-4 for the cladding.  A reference fuel pin file was
also added.
Added justifiction for printing
Added 10 um MCNP files

Added 10 um MCNP simulaiton files
updated git ignore
Renamed mcnp files

Renamed the mcnp input decks to shorten up the files names a little bit.
The .mcnp extension should give it away.
Updated README for MCNPX Model

Updated the README for the MCNPX model. I don't quite understand why
there is a dispgrepancy between the MCNPX model and the XSDRN model.  I
am a little bit worried about how MCNPX goes about calculating the
atomic density, as (if the weight fraction is determine by a ratio of
denisities) then it might think that N is a gas.