Separate the distribution version# from the .jar and .so version#

Separate the version# for the .jar and .so files from the version# used in the .jar and .so file. This is useful for doing backwards compatibility of catalogs where we want a fixed version.txt so that no recompile is needed during an upgrade, but want the kit to have a newer version# for the .tar.gz distribution and the directory it unpacks.

To set this call ant with -Ddist.version=w.x.y.z (or any string, as this version# is only used for filenames). 

Other info:
- this has no impact on -Dbuildstring="..." which overrides the calculated buildstring.txt.  This is just package naming.  The version# in -Dbuildstring should match the version.txt, not the dist.version number.
- None of this should ever go to master. Master has real catalog compatibility and real rolling hotfix abilities.
- The files in the voltdb/ will have the real version.txt info so that loading works.