text: more Git updates

A few updates for Git that were missed, including the new version
numbering scheme for nightly snapshot tarballs.
distscript: whitespace cleanup, remove ancient kruft

There was some (almost) wholly-commented out code in here that reaches
back to the beginning of the project.  Just delete it.
distscript: remove configure.params and autogen.subdirs kruft

Remove configure.params support: configure.params hasn't been used in
years.

Also remove autogen.subdirs support; those should really be handled by
their respective Makefile.am's.
version configury: make dist now works

Update the VERSION file scheme:

* Remove "want_repo_rev".
* Add "tarball_version".

All values are now always included (major, minor, release, greek,
repo_rev).  However, configure.ac now runs "opal_get_version.sh
... --tarball", which will return the value of tarball_version (if it
is non-empty) or the "full" version string (i.e.,
"major.minor.releasegreek").
build server: moved scripts to contrib/build-server

Removed a redundant copy of the scripts running on the build server
and moved the remaining copy out to a top-level directory in contrib
(i.e., contrib/build-server vs. contrib/dist/build-server, where I
never could remember where to find them).
make_dist_tarball: updates for git

Several updates, including:

* Remove -single dash options
* Don't chmod the whole tree; just chmod the files we're trying to remove
* No more support for SVN or HG; 100% git
* Strengthen the dirty repo checks
* Use git describe for the repo version
* Set tarball_version to "" (i.e., empty) in VERSION
make-authors.pl: update for git
AUTHORS: Updated with Git email addresses (vs. SVN IDs)
create_tarball.sh: make it executable