shell script to make data

The `./scripts/runall.sh` script downloads XML files that contain the tables and converts them to CSV. This was a nice project to force me to hone my shell scripting skills, so forgive me if my first attempt is not elegant. I run Windows with Cygwin, but to my knowledge this should be cross platform.

There were changes to the `codes-all.csv` output. It looks like there has been a new release of the tables (published 28 March 2014) since the first package, so there were some elements that changed.

All of the changes fall into one of the following categories:

1. The "remarks" column is empty. I cannot find this information anywhere
  (XLS or XML on website). Maybe it was removed in the new data release?
2. Many small spacing changes (e.g. "European Union " to "European
   Union")
3. Inconsequential changes (e.g. "Unidades de formento" to "Unidad de
   Fomento")
4. Actual changes (e.g. "PALESTINIAN TERITORY, OCCUPIED" to "PALENSTINE,
   STATE OF")
5. Movement from "current" to "historical" list ("LATVIA,Latvian Lats",
   "ZZ05_UIC-Franc")
6. The "—", "Nil", and "N.A" characters in the 4th column,
  [as mentioned in issue 3](https://github.com/datasets/currency-codes/issues/3)
  have disappeared, presumably because of the XML files have no tags for the
  effected rows.

This commit would solve [issue 3](https://github.com/datasets/currency-codes/issues/3)