Fixed bug in handling of a 32-bit execve on a 64-bit program.
This fixes a bug reported by Stefan Kluth when using ATLAS
software via CVMFS.
Changed micro field of version to string.
Use size of incoming file when checking if the available disk space is within
the specified threshold.
Added -E option to work_queue_pool to allow adding extra worker options (in addition to the already supported -t -C -N -o options) to the workers managed by the pool.

For example, if you run the following:
    work_queue_pool -a -N myproj -E '-b 120 -o mydebug')

The '-b 1200 -o mydebug' options would be added to every worker started by this pool.