Generate more detailed version information.

New output with git with local changes when URL is unavailable:
flashrom v0.9.7-r1716-50e143e-2-dirty on Linux 3.8.0-6-generic (x86_64)
modified 2013-08-21T14:34:40+0200

Signed-Off-By: David Hendricks <dhendrix@google.com>
Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>