Include user and build host in version string

Make the version string used in AFSVersion and cml_version_number
include the names of the user doing the build and the host on which
it is done.  Also, remove extraneous whitespace and the content-free
word 'built' from cml_version_string, since Rx debug packages provide
space for only 64 characters of version string.

Change-Id: I128f6c175bb93b1fb5a4d531f64aa81bd2841ce7
Reviewed-on: http://gerrit.openafs.org/2279
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>